Infusion pump system and related methods

ABSTRACT

An infusion pump system including an infusion tubing for delivering a fluid, a heat exchanger cartridge in fluid communication with the infusion tubing and removably coupled to at least one thermal element for heating or cooling the fluid, a motor driven pump in mechanical communication with the infusion tubing and configured to pump the fluid through the infusion tubing and the heat exchanger cartridge, and a central controller in electrical communication with the motor driven pump and the at least one thermal element. The central controller is configured to selectively deliver the fluid to a patient without heating or cooling the fluid by causing the motor driven pump to pump the fluid through the infusion tubing and the heat exchanger cartridge while the thermal element is off.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. patentapplication Ser. No. 13/750,254 filed Jan. 25, 2013, which is acontinuation of U.S. patent application Ser. No. 11/835,118 filed Aug.7, 2007, now U.S. Pat. No. 8,360,737, which is a continuation-in-part ofU.S. patent application Ser. No. 11/082,260 filed Mar. 17, 2005, nowU.S. Pat. No. 7,563,248, which are incorporated by reference in theirentirety herein.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

This invention was made possible at least in part with the assistance ofU.S. Grant No. DAMD 17-02-01-0700 awarded by the United States Army, andthe government may have certain rights therein.

FIELD OF THE INVENTION

The present invention is directed to an infusion device having adisposable cartridge for warming and/or cooling fluid that connects witha pump housing and allows for simple, accurate control of infusion flowrates and/or infusion pressures.

BACKGROUND

Fluid required in treating a patient must often be stored incomparatively cool to cold temperatures with respect to the patient'sbody temperature. This often refrigerated storage is necessary topreserve the fluids in a state so the function and integrity of thefluid is maintained. Fluids such as blood and other bodily fluids aretypically stored at hypothermic temperatures ranging from 2° to 20°Celsius. Therefore, when introducing fluids into the patient's body itis often necessary to heat the fluid to an appropriate temperature notonly to prevent any rapid decrease in the patient's body temperature,but also to ensure that the fluid being introduced can function asneeded. It is known that the injection of cold fluids into a patient'sbody can create a major source of conductive heat loss within thepatient, often placing the patient at further risk by cooling, tooquickly or, to a temperature where physiological damage can occur.

In heating or warming the fluid, however, care must be taken to ensurethat the heating itself does not create a further complication. Forinstance, if blood reaches a certain temperature then hemolysis, thedestruction or severe degradation, of the blood cells can occur.Likewise, if the fluid is heated too high and then introduced into thepatient's body, physiological damage resulting from exposure toexcessive temperatures such as burns or other such scarring can occur.Heating the fluid in bulk form usually requires the application of toointense a heat source in order to heat the entire fluid with any levelof time efficiency. Likewise, heating the fluid over a prolonged periodof time can lead to increased exposure of the material to theenvironment creating risks of contamination.

Getting the fluid into the patient requires adjustable flow so that theproper amount of fluid depending upon the need is provided to thepatient. Combining the fluid delivery means with the proper andefficient heating of the fluid is crucial to the proper delivery offluid to the patient. The prior art contains systems for warming fluidsas they are infused into a patient. The manner in which the fluids areheated within these systems varies and can be accomplished viaconvection or conduction. An example of a system which poses clinicalproblems heats the fluid being delivered to the patient via exposure toa heated fluid, such as water. Such systems are usually cumbersome,require frequent cleaning, and can pollute the clinical environmentthrough the introduction of an additional substance—the heating liquid.Such a system often places a conduit through a liquid such as water,which is then heated, and the fluid to be delivered to the patient isdrawn through the conduit thereby increasing the temperature of thefluid to be delivered. Such a system can be deleterious to a sterileenvironment and may not be properly transported. Furthermore, thesesystems also have large mass, which require significant power to heatthat mass yielding a significant time to achieve that temperature, orachieve a stasis when a cold mass (like a bag of chilled fluid) isintroduced. An additional problem to be avoided is the danger to thepatient caused by current leakage in the system circuitry andspecifically the circuitry used to achieve the warming characteristicsthat may be in close contact to the blood being infused to the patient.Capacitive coupling, the transfer of energy from one element to anotherby means of mutual capacitance, could possibly cause enough currentleakage to the heating system, and, potentially, to the patient andcause electric shock. It is, therefore, important to reduce the amountof capacitive coupling between the heating system and the heatingexchanger, thus reducing the potential for current leakage and reducingthe risk of causing electric shock to the patient, while at the sametime creating efficient heating of the blood.

Moreover, during some fluid infusion procedures it is beneficial toadjust the temperature of the patient's body either warmer or cooler. Assuch, it is extremely beneficial to have an adjustable in-line fluidwarming or cooling system so that the proper temperature can beregulated. In instances of massive or emergent fluid loss, it is oftennecessary to infuse (and sometimes recover and re-infuse) extremelylarge amounts of fluid into the patient's body. In such instances,traditional fluid heating systems often place the fluid at risk byexposure to temperatures which could damage the fluid because the fluidmust be heated so rapidly. Furthermore, whereas existing patient coolingmethods include practices such as externally applying cooling blankets,it will be beneficial to provide a system that more efficiently andrapidly cools a patient's core body temperature. Such problems remainlargely unsolved by the art; and the need for better in-line fluidinfusers is abundant.

Similarly, studies have shown that symptoms and harmful effects ofcertain conditions may be reduced by inducing hypothermia. For example,it has been demonstrated that circulating cooled blood before or duringischemia reduces the infarct size or slows the effects caused byinfarction. Similarly, other studies show that cooling patients aftersuffering an acute stroke reduces metabolism and inflammation, bothfactors affecting ischemia induced by stroke. Thus, there also exists aneed for a means to accurately cool fluid, like blood, and control flowrates of the cooled fluid.

When introducing fluid into a patient's body (e.g., the circulatorysystem) it is crucial that air not be introduced into the patient's bodyas well. Introduction of air or air bubbles into a patient's body (e.g.,the circulatory system) can cause extremely deleterious effects. Airembolisms can occur if air accumulates in a patient's blood streamresulting in cardiac arrhythmias, stroke, or pulmonary infarct. Any ofthese potential infirmities can be life threatening and need to beminimized in situations where high volumes of fluid are being infused.It is therefore extremely important that during infusion of fluid thatboth the monitoring of air in the infusion system occurs to preventintroduction into the patient's body.

Devices in the prior art seeking to warm fluid for infusion into thebody often suffer from very specific problems. For example, the heatersystem described in U.S. Pat. No. 3,590,215 issued to Anderson et al.uses regions of differing heat which the fluid encounters as itprogresses through the system. Specifically, the heating element orelements described in Anderson et al. diminishes the heat in thematerial warming the fluid from a hottest temperature where the fluidenters the heat exchanger to a coolest temperature where the fluid exitsthe heat exchanger. Such a configuration not only makes it difficult toregulate the temperature of the fluid as the flow rate changes, but italso runs the risk of having to expose the fluid to temperatures abovewhich the fluid should be exposed to, running the risk of damaging thefluid.

Likewise, the serpentine fluid flow path described in Anderson et al.creates the typical laminar type flow seen in most heat exchangersystems. For example, U.S. Pat. No. 5,245,693 to Ford et al. describes aserpentine flow pattern which is long compared to its width and widercompared to its depth. This type of flow is consistent with anon-turbulent laminar type flow path. A non-turbulent flow path requiresadditional heat energy to be introduced into the fluid system or longerexposure to the heating in order to increase the temperature of thefluid system uniformly to a desired temperature.

In addition to heating the fluid efficiently, a variety of clinicalcircumstances, including massive trauma, major surgical procedures,massive burns, and certain disease states such as pancreatitis anddiabetic ketoacidosis can produce profound circulatory volume depletion,either from actual blood loss or from internal fluid imbalance. In theseclinical settings, it is often necessary to infuse blood or other fluidsrapidly into a patient to avert serious consequences.

Intravenous infusion rates may be defined as either routine, generallyup to about 999 cubic centimeters per hour, or rapid, generally betweenabout 999 cubic centimeters per hour and about 90,000 cubic centimetersper hour (1.5 liters per minute) or higher. Most existing infusion pumpsare designed for medication delivery and are limited in theirperformance to the routine range of infusion rates. Such pumps are notcapable of rapid intravenous infusion. Although some prior infusionsystems can deliver rapid infusion, those prior rapid infusion devicesare physically large, complex systems that require dedicated operationby skilled technicians. For example, U.S. Pat. No. 6,942,637 issued toCartledge et al. describes a rapid infusion system having a differentialdrive that interacts with multiple motors to achieve the variablepumping rates desired. U.S. Pat. No. 6,942,637 specifically describes adifferential drive that includes, among other components, multiplemotors, such as a high speed motor and a stepper motor, and acombination of gears mechanically linking the multiple motors to acommon drive shaft.

In other uses, a fluid pump system may be used for fluid delivery duringcertain surgical procedures, such as arthroscopic surgeries, to distendthe area of operation. For example, saline solution is infused into thejoint during an arthroscopy to expand the joint and clear the surgicalfield of view. However, current technologies are deficient in allowingthe control of both the pressure and temperature of the fluid so as tonot cause excessive cooling or warming of the area.

Accordingly, what is needed is a pump device for variably controllingfluid flow rates, fluid flow pressures, and fluid temperatures that iscompact and easily operated by medical personnel in the course of theirother duties. What is also needed is a low-to-high speed pump devicethat may heat or cool fluid efficiently and safely, that utilizes asterile, disposable fluid containment system that can be readilyattached and removed from a separate pumping mechanism.

SUMMARY OF THE INVENTION

Described is a system for controlling the flow and temperature of afluid being infused into a patient's body while the infusion is takingplace. Such a pump system is also referred to as an, an infusion system,or an in-line heating or cooling infusion system. The system alsoprovides for improved monitoring of air in the infusion system such toprevent the introduction of air into the patient's body receiving thefluid infusion. The pump system also provides variable flow rates andflow pressures that may be dynamically controlled by way of anelectronically controlled motor, that serve a vast amount of infusionneeds. The pump system may also be controlled through a simple userinterface to a system having stored logic and data collectioncapabilities that allows for simple and accurate control of the system.Improved heat exchange efficiencies through advantageous constructionand circuitry of the system components are also provided for while alsoreducing the risk of sustaining electric shock by the patient. Thecomponents of the disposable cartridge align with their respectivecomponent mates on the pump housing, so as to make attaching thedisposable cartridge to the pump housing and operation simple andeffective.

More specifically, the pump system may include infusion tubing, apumping mechanism, a motor drive assembly, a user input control, and anelectronic controller. The electronic controller may include a digitalsignal processing controller that is configured to cause power to besupplied to the motor drive assembly in response to user input. The pumpsystem may selectably deliver fluid at rates from about 1 milliliter perhour to at least about 3000 milliliters per minute, and to about 8000milliliters per minute in some embodiments. The digital signalprocessing controller may be a high resolution digital signal processingcontroller including between an approximately 16-bit to an approximately64-bit registry, or in some embodiments a 32-bit registry.

In another example of the pump system provided for, the pump system mayinclude fluid tubing and a roller head pump communicating with the fluidtubing configured so as to improve flow rate accuracies. The fluidtubing may be secured to the pump system both immediately before andimmediately after the fluid tubing communicates with the roller headpump. Securing the fluid tubing to the pump system assists to maintain asubstantially constant length and a substantially constant tension ofthe portion of the fluid tubing in communication with the roller headpump, thereby reducing undesired variation in the fluid tubing behaviorduring pump and improving flow rate accuracies.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an elevation view of the internal elements of a disposablecartridge in accordance with an example of the present invention.

FIG. 2a shows a different orientation of the disposable cartridge inaccordance with an example of the present invention (near cover ofdisposable removed).

FIG. 2b shows the side of the disposable cartridge of an example of thepresent invention which abuts the pump housing.

FIG. 2c shows the pump housing with exposed platen embodying an exampleof the present invention.

FIG. 2d shows the pump housing as it aligns with the disposablecartridge in accordance with an example of the present invention.

FIG. 3 shows one-half of the heat exchanger—one plurality of fins—inaccordance with an example of the present invention.

FIG. 4 shows a cross-section of the heat exchanger, artificiallyhollowed, showing a fluid flow path in accordance with an example of thepresent invention.

FIG. 5 shows an outside view of an air-trap in accordance with anexample of the present invention.

FIG. 6 shows a cross-section of an air-trap in accordance with anexample of the present invention.

FIG. 7 shows the shape of fluid that would fill a heat exchanger inaccordance with an example of the present invention.

FIG. 8a shows an exploded view of an exemplary heating element inaccordance with an example of the present invention.

FIG. 8b shows an exploded view of an exemplary cooling element inaccordance with an example of the present invention.

FIG. 9 shows a transparent view of an exemplary heating element,including a plurality of heat points in accordance with an example ofthe present invention.

FIG. 10 shows a motor drive assembly and pumping mechanism that would beintegrated within the pump housing in accordance with an example of thepresent invention.

FIG. 11 shows an exemplary functional block diagram of the electronicmotor controller in accordance with an example of the present invention.

FIG. 12 shows an exemplary user interface panel and the status displaypanel in accordance with an example of the present invention.

FIG. 13 shows an exemplary flow chart illustrating the steps ofoperation in accordance with an example of the present invention.

FIG. 14 shows an exemplary flow chart illustrating the steps to executeautomatic priming in accordance with an example of the presentinvention.

FIG. 15 shows an exemplary flow chart illustrating the steps to executemanual priming in accordance with an example of the present invention.

FIG. 16 shows an exemplary flow chart illustrating the steps to controltemperature in accordance with an example of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

A disposable heat exchange cartridge and pump device for use duringfluid infusion into a patient's body is described. The disposable heatexchange cartridge is removably coupled to an infusion pump device whichprovides not only the energy or power required to heat or cool the fluidbeing infused, but also provides, the flow generating pump andmechanisms for monitoring and regulating particular aspects of the fluidpumping system. More specifically, the disposable heat exchangecartridge may include a heating element disposed in the pump device bymeans that increase the efficient transfer of heat energy, while alsoproviding safe and simple operation of the system. Alternatively, thedisposable heat exchange cartridge may include a cooling elementsimilarly disposed to cool the temperature of the fluid. Additionally,the disposable heat exchange cartridge has components that areadvantageously aligned with their respective component mates on the pumpsystem, allowing for simple attachment and detachment. Furthermore, thepump device includes a simple user interface that allows for accuratecontrol of the pump device and the collection of operation-related data.In this description of the invention, reference will be made to theembodiments shown in FIGS. 1-16 wherein like numerals are used todesignate like parts throughout. FIGS. 2a-2d describe a currentlypreferred embodiment of the present invention and should not be viewedas limiting.

One aspect described herein is a pump system that includes an infusiontubing, a pumping mechanism, a motor drive assembly in mechanicalcommunication with the pumping mechanism, a user input control, and anelectronic controller in electrical communication with and at leastpartially controlling the motor drive assembly. The electroniccontroller includes a digital signal processing controller in electricalcommunication with the motor drive assembly that is configured toreceive a signal from the user input control and to cause power to besupplied to the motor drive assembly in response at least partially tothe signal from the user input control. The pump system may selectablydeliver fluid at rates from about 1 milliliter per hour to at leastabout 3000 milliliters per minute, and in other embodiments to about8000 milliliters per minute.

In one embodiment described herein, the digital signal processingcontroller may be a high resolution digital signal processing controllerincluding between an approximately 16-bit to an approximately 64-bitregistry, or in some embodiments a 32-bit registry. The pump system mayfurther include motor power drive circuitry in electrical communicationwith the digital signal processing controller and with the motor driveassembly, wherein the digital signal processing controller is configuredto send to the motor power drive circuitry a pulse-width modulationsignal that causes the power motor drive circuitry to apply apredetermined level of voltage intermittently to the motor driveassembly. In some embodiments the motor power drive circuitry may be anH-bridge circuit. The digital signal processing controller may be aProportional Integral Derivative filter and may have betweenapproximately 8-bit to approximately 24-bit coefficients. The pumpsystem may further include at least one of a tachometer or an encoder incommunication with the motor drive assembly and the digital signalprocessing controller, wherein the tachometer or encoder communicatesthe speed of the motor drive assembly to the digital signal processingcontroller. In one embodiment the pump system includes a high resolutiontachometer having between approximately 250 lines of resolution toapproximately 1000 lines of resolution.

In one embodiment described herein, the motor drive assembly may includea DC motor mechanically coupled to a gearbox and in electricalcommunication with the electronic controller. The gearbox may bemechanically coupled to the pumping mechanism and may include aplurality of gears configured in a fixed ratio that does not changeduring operation. In one embodiment the motor drive assembly includesonly a single DC motor to achieve the variable flow rates. The pumpingmechanism may be a roller head pump, a non-circular peristaltic pump, acentrifugal pump, an impeller, or the like. In one embodiment thepumping mechanism is a roller head pump comprising at least two rollers,and in one embodiment three rollers, in communication with the infusiontubing.

In another embodiment described herein, the pump system further includesa disposable cartridge housing the infusion tubing and a pumpingmechanism with a roller head pump. The infusion tubing may be secured toat least a first point on the disposable cartridge before the infusiontubing communicates with the roller head pump and to at least a secondpoint on the disposable cartridge after the infusion tubing communicateswith the roller head pump. Securing the infusion tubing to thedisposable cartridge maintains a substantially constant length and asubstantially constant tension of the portion of the infusion tubing incommunication with the roller pump head. In one embodiment the infusiontubing may include a primary inflow tube having a first end and a secondend, a pump loop tube having a first end and a second end, wherein thefirst end is coupled to the second end of the primary inflow tube at thefirst point on the disposable cartridge, and a pump outflow tube havinga first end and a second end, wherein the first end is coupled to thecoupled to the second end of the pump loop tube at the second point onthe disposable cartridge.

In some embodiments described herein, the electronic controller mayincrement or decrements infusion rates in increments between about 1milliliter per hour to about 200 milliliter per minute per user request.Further, the electronic controller may rapidly adjust infusion ratesbetween 1 milliliter per hour and 3000 milliliter per minute, or toabout 8000 milliliters per minute in some embodiments. The pump systemmay deliver blood, crystalloid, colloid, saline, medicine, or the liketo a patient. In some embodiments, the pump system may delivernormothermic fluids to a patient. The pump system may further include acontrol panel that receives a user input and transmits a signal to atleast one of the motor drive assembly or the electronic controller inresponse to the user input.

In one embodiment described herein, the pump system may further includeat least one of a heating element or a cooling element, and a heatexchanger removably coupled to the heating element or cooling elementand configured to receive and pass therethrough fluid from the infusiontubing as a result of the operation of the pumping mechanism.

One aspect described herein is a pump system including at least oneinfusion tubing, a pumping mechanism, a motor drive assembly inmechanical communication with and rotateably driving the pumpingmechanism, and a digital signal processing controller configured toreceive at least one user input and to cause power to be supplied to themotor drive assembly in response at least partially to the user input.The digital signal processing controller may be a high resolutiondigital signal processing controller including between an approximately16-bit to an approximately 64-bit registry, or in some embodiments a32-bit registry. Further, in some embodiments having a digital signalprocessing controller, a motor power drive circuitry and a highresolution tachometer or a high resolution encoder, as described aboveare also included.

In another embodiment described herein, the pump system may deliverfluid at a substantially constant flow rate between about 1 milliliterper hour and at least about 3000 milliliters per minute, or to about8000 milliliters per hour in other embodiments. The substantiallyconstant flow rate may be variable in response to receiving a seconduser input after the initial user input. In some embodiments the pumpsystem is capable of maintaining a substantially constant flow pressurebetween about 0 mmHg and about 750 mmHg, or between about 25 mmHg andabout 150 mmHg in other embodiments. The substantially constant flowpressure may be variable in response to receiving a second user inputafter the initial user input. Further, the pump system may be configuredso that a subsequent user input supersedes a previous user input andcauses a response in the pump system.

One aspect described herein is a pump system that includes fluid tubingand a roller head pump communicating with the fluid tubing. The fluidtubing may be secured to at least a first point on the pump systembefore the fluid tubing communicates with the roller head pump and to atleast a second point on the pump system after the fluid tubingcommunicates with the roller head pump. Securing the fluid tubing to thepump system maintains a substantially constant length and asubstantially constant tension of the portion of the fluid tubing incommunication with the roller head pump, thereby reducing undesiredvariation in the fluid tubing behavior during pump and improving flowrate accuracies.

In one embodiment described herein, the fluid tubing includes a primaryinflow tube having a first end and a second end, a pump loop tube havinga first end and a second end, wherein the first end is coupled to thesecond end of the primary inflow tube, and a pump outflow tube having afirst end and a second end, wherein the first end is coupled to thecoupled to the second end of the pump loop tube. Further, the first endof the pump loop may be coupled to the second end of the primary inflowtube at the first point on the pump system, and the first end of thepump outflow tube may be coupled to the second end of the pump loop atthe second point on the pump system. The pump system of this embodimentmay further include a pump housing and a cartridge removably connectedto the pump housing, wherein the first point and the second pointcorrespond to the cartridge, the fluid tubing is at least partiallyintegrated with the cartridge, and the roller pump head is at leastpartially integrated with the pump housing.

In one embodiment, a heat exchanger 101, as depicted in FIG. 1, iscontained within a disposable cartridge 100. The disposable cartridge100 is removably attached to a pump system such that once the treatmentis completed, the disposable cartridge 100 can be removed and discarded.The disposable cartridge 100 is self-contained and, once attached to thepump system, need not be adjusted or manipulated. Fluid enters thedisposable cartridge 100 in the primary inflow tube 102, which drawsfluid from the fluid source. The fluid is drawn into the primary inflowtube 102 and flows past an inflow bubble detector 120, which is furtherdescribed in reference to FIG. 2d . The inflow bubble detector 120 maybe an ultrasonic sensor that sends a signal across the inflow tube 102.In other embodiments, the bubble detector 120 may be an optical-basedsensor, such as a laser sensor, or the like, as is known in the art, todetect a change in the fluid properties, and thus the presence ofbubbles. Attenuation in the signal reaching a certain predeterminedlevel, indicating no fluid in the system, may cause the system to stoppumping. After the fluid flows past the inflow bubble detector 120, thetemperature is sensed by the inflow temperature sensor 260, which isfurther described in reference to FIG. 2d . The inflow temperaturesensor 260 may be an infrared temperature sensor. In other embodiments,the inflow temperature sensor 260 may be an optical temperature sensor,such as a laser sensor, a thermistor, or the like, as is known in theart. The inflow bubble detector and inflow temperature sensor may beintegrated with the pump housing and align with one of at least twodetector interfaces 230 on the disposable cartridge and communicate withthe primary inflow tube, as is described in reference to FIG. 2d . Theinflow temperature sensor 260 may provide the fluid temperature, beforeentering the heat exchanger, as an input to a central controller toallow for more accurate control of heating or cooling elements,described further herein. Next, the fluid proceeds past a firstt-junction, which serves as the inflow pressure junction 103. The inflowpressure junction 103 is in fluid communication with a first air chamber151. The inflow pressure junction 103 and the first air chamber 151communicate with pressure sensors on the pump housing to determine thepressure of the fluid flow as it enters the pump loop 104 to allow forproper regulation of the fluid flow. The pump loop 104 interacts with apump device, as described in reference to FIG. 10. The pump loop 104,when interacting with a pumping system, pushes the fluid through theremainder of the disposable cartridge 100. When the fluid leaves thepump loop 104 it flows through a second t-junction, which serves as thepump outflow pressure junction 105. The pump outflow pressure junction105 and another air chamber may communicate with sensors on the pumpdevice to determine the pressure of the fluid as it exits the pump loop104, so that the pressure of the fluid through the disposable cartridge100 can be regulated. In one embodiment, the pump loop 104 may be adifferent tube coupled to the primary inflow tube 102 and a pump outflowtube 109 and securely affixed to the disposable cartridge 100.

The fluid then passes into the heat exchanger 101 via the exchangerinlet port 106 at the lower aspect of the heat exchanger. In the abovedescribed embodiment including a pump outflow tube 109, the pump outflowtube 109 couples with the exchanger inlet port 106 of the heatexchanger. After the fluid passes through the turbulent environmentestablished by the heat exchanger 101, it exits via the exchanger outletport 107 located at a position opposite the exchanger inlet port 106 atthe upper aspect of the heat exchanger 101. At this point, the fluid forinfusion has undergone its warming or cooling and the desiredtemperature has been reached. A heat exchanger temperature sensor 287,as described in reference to FIG. 2d , is positioned on the pump housingand communicates with the heat exchanger 101 to sense the temperature ofthe heat exchanger, and thus a relative temperature of the fluidcontained therein. In an alternative embodiment, a temperature sensormay also be placed internally within the heat exchanger 101 so as to bein direct contact with the fluid contained therein. In a manner similarto that of the inflow temperature sensor 260 described above, the heatexchanger temperature sensor 287 may provide the heat exchangertemperature as an input to the central controller for controlling theoperation of the heating or cooling elements. For example, if the heatexchanger temperature sensor senses a temperature greater or lower thana predetermined maximum, for example 45° Celsius when heating, thecentral controller may limit or stop power to the heating or coolingelement and may cause the infusion device to stop pumping fluid to thepatient. The heat exchanger temperature sensor 287, or the temperaturesensor positioned internally within the heat exchanger just described,may be a contact thermocouple, or the like, as is known in the art.

The fluid exits the heat exchanger 101 via the exchanger outlet port107, and then enters the air-trap 110 at about the mid-point along thelong-axis of the air-trap 110. Fluid flows out of the air-trap 110 andthrough a third t-junction, which serves as the fluid outflow pressurejunction 135. Similar to the inflow pressure junction and pump outflowpressure junction, the fluid outflow pressure junction 135 and anotherair chamber may communicate with sensors on the pump device to measurethe pressure of the infusion fluid prior to delivery to the patient. Thefluid outflow pressure junction 135 assists in allowing for the controlof the infusion pressure so pressure can either be substantiallymaintained at a pre-defined pressure, or kept within a pre-definedmaximum or minimum limit. Next, prior to delivery to the patient, thefluid is sensed by the outflow bubble detector 112 and subsequently theoutflow temperature sensor 261, aligning with another bubble detectorinterface 230, in the same manner as is described for the inflow bubbledetector and inflow temperature sensor, described above and further inreference to FIG. 2d . The outflow bubble detector 112 determineswhether excess amounts of air have infiltrated the system. If anunacceptable level of air remains in the fluid as it flows past theoutflow bubble detector 112, the system may not allow infusion of thefluid into the patient's body. If the fluid contains no air, or aminimal amount of air such to be acceptable, the fluid passes theoutflow bubble detector 112 and into the patient via the primary outflowtube 111. The outflow temperature sensor 261 measures, for example,using an infrared sensor as is known in the art, the temperature of theinfusion fluid prior to delivery to the patient. Thus, if the fluidtemperature exceeds pre-defined limits, the outflow temperature sensor261 can signal to the device to stop pumping and subsequently alter theheating controls, or alternatively stop the device entirely. In otherembodiments, the outflow temperature sensor 261 may be an opticaltemperature sensor, such as a laser sensor, a thermistor, or the like,as is currently known in the art.

A detailed description of the heat exchanger 101 requires reference toFIGS. 3 and 4. Heat exchanger 101 can be created by two halves cast fromthe same mold, each containing a plurality of fins. A first half 301 iscomprised of the exchanger inlet port 106 and a plurality of finscomprising a series of spaced fins 302. With the exception of aspecially sized flow fin 303, each of the fins 302 are of equal size andare spaced equidistant from one another. As fluid enters the heatexchanger 101 through the exchanger inlet port 106, the fluid fills theflow cavity 304 defined by the inner walls of the heat exchanger and theflow fin 303. When in operation, the heat exchanger is oriented suchthat a lower aspect, where the inlet port 106 is located, and an upperaspect, where the outlet port is located, are oriented in a verticalform, forcing fluid to flow in an upwardly direction through the heatexchanger and against gravitational forces. Because of the special shapegiven the flow fin 303, the fluid fills the flow cavity 304 beforeproceeding up through the heat exchanger 101. An alternate embodiment ofthe heat exchanger 101 may be constructed from two dissimilar halves,where the half farthest from the heating or cooling element has agreater mass. Similarly, in an embodiment having dissimilar halves, anynumber of fins 302 may be included having any spacing therebetween,because symmetry is not required. Though, it is appreciated that thefirst embodiment, having symmetrical halves constructed from the samemold, is the preferred embodiment considering manufacturing costs.

Using FIG. 4 to describe the flow of fluid through the heat exchanger101, fluid enters the flow cavity 304 via the exchanger inlet port.Because of the differentially sized flow fin 303, fluid preferably firstfills the flow cavity 304 before rising over the first fin. Thispreliminary filling allows the fluid to fill the width of the heatexchanger and flow as a wide ribbon of fluid across the fins—opposed toa laminar flow through a long but narrow conduit. The flow fin 303accomplishes the appropriate spreading of fluid by creating a thinnerflow gap 305 between the flow fin 303 and the first of the plurality offins of regular shape. The fluid then flows up the length of the heatexchanger 101 between the exchanger inlet port and the exchanger outletport. As the fluid rises, it travels in wave form as a shallow, butwide, ribbon of fluid. The wide-flow, short linear track flow patterncreated by the heat exchanger, creates a turbulent flow causingincreased molecular circulation within the fluid. While laminar flowwithin typical conduits, such as tubes, see higher molecular “turnover”in the central portion of the conduit, the turbulent flow within theheat exchanger 101 provides much more exposure of different molecules tothe interior surface of the heat exchanger thereby facilitating moreefficient and effective energy transfer.

It is appreciated that in other embodiments the heat exchanger 101 maybe constructed so as to cause a discrete flow path, rather than adisruptive, laminar flow path, as previously described. For example, aheat exchanger configured in this manner may not have fins, but insteadmay provide a distinct path by a series of flow walls, for example, in aserpentine-type flow path, so as to increase exposure of the fluid tothe thermally conductive heat exchanger. It is further appreciated thatother means of directing flow through a heat exchanger, so as toefficiently facilitate heat transfer, as are known in the art, may beemployed.

Returning to FIG. 3, the other half of the heat exchanger can be createdfrom the same mold, wherein the exchanger inlet port 106, becomes theexchanger outlet port. Once formed, the two halves are mounted together,using means known in the art, including, but not limited to, bolts,screws, or other mechanical means, as well as glues, cements, or otherchemical means. If mechanical means are used, then fixation tabs 306 canbe used to house the fixation devices.

A further benefit achieved by creating the heat exchanger 101 from thesame mold is that all surface areas in which the infusion fluid contactswill be the same highly conductive material, such as anodized aluminum,as further described below. Rather than creating only the half of theheat exchanger 101 that will communicate with the heating element of thepump housing made from highly conductive material and creating the outerhalf of the heat exchanger 101 from an insulative material, as one mightintuit would reduce temperature loss, also creating the outer half fromhighly conductive material, provides further surface area and greatermass to transfer heat from the heating element or to the cooling elementof the pump housing, through the heat exchanger 101, and to or from theinfusion fluid. Thus, as the heating element transfers heat to the heatexchanger 101, heat is dissipated to the plurality of fins 302 from boththe interior half and the outer half. Similarly, the cooling element maycool the heat exchanger by cooling the plurality of fins 302 by coolingthe two halves.

FIG. 4, the cross-section view of the heat exchanger further shows theseal seat 401, which provides for a space to place a seal about thecircumference of the heat exchanger to increase the liquidimpermeability of the heat exchanger, such as an o-ring. It should benoted that while the heat exchanger of the present embodiment isdescribed as being formed from two identical halves, the heat exchangercould be formed as a singular piece, or more than two pieces, and frommore than one asymmetric mold. For ease in manufacture, however, twoidentical halves, as described herein, allows for the proper resultthrough less cost.

The heat exchanger of the present invention can be formed from anynumber of thermally conductive materials, such as: cast anodizedaluminum, copper, gold, silver, carbon foam, ceramics, and the like, asis known in the art. The material chosen for use in the heat exchangerof the present invention must be capable of adequate heat conduction anddispersion to ensure proper heat distribution across the surface, aswell as heat transfer to or from the fluid desired to be warmed orcooled. Thermodynamics dictates that for two materials with the samespecific heat, that is the amount of heat energy required to change thetemperature of the material one unit per unit of mass, the material witha greater mass will more efficiently transfer heat to the material witha lesser mass. This efficiency level is often understood as thermalcapacitance—in that materials with greater thermal capacitance (i.e.mass) will retain more heat while transferring energy to the adjacentmaterial, sufficient to greatly increase the temperature of the secondmaterial, without the unwanted loss of energy. Analogizing the heatexchange occurring between the heat exchanger and the infusion fluid tobe warmed by way of example, a material with a mass of 1.5 kilograms isheated to 60° Celsius and placed in close, direct contact with amaterial having a mass of 0.5 kilograms at a temperature of 40° Celsius.When the heating is complete, both materials will achieve a temperatureof 55° Celsius. The energy stored by the hotter component, via itsincreased mass, allows for a better exchange of heat energy between thetwo materials. The converse is also true, by which the component withthe increased mass is cooled. The selection of a material, given thespecial requirements of the present invention, therefore requires theconsideration of the mass of the material, as well as the thermodynamicproperties of that material.

FIG. 5 shows an enlarged view of the air-trap 110 and its connectiveconduits. While the air-trap is described with reference to specificshapes, it should be apparent to one of skill in the art that any shapewhich would allow for the reversal of fluid flow direction at the fluidoutput port of the air-trap will allow for the monitoring and removal ofair from the cartridge system. The air-trap 110 is generally cylindricalin shape with a domed top 501 and flattened bottom 502. Fluid enters theair-trap 110 at the air-trap intake port 503, located at approximatelymidway along the long axis of the air-trap. Fluid enters the air-trap110 from the heat exchanger in order to remove any air trapped orintroduced into the fluid. The air to be removed may have come fromfailure to purge the fluid source of air before introducing it to thepresent invention. It is also possible that the heating of the fluidcauses the release of bound gas, creating bubbles, which, if allowed toenter the patient's body, could be deleterious or even deadly. Fluidexits the air-trap 110 through the fluid output port 505 located at thebottom 502 of the air-trap.

FIG. 6 depicts a cross-section of the air-trap 110. In this view, onecan see the air-trap intake port 503 as it interfaces with the air-trap110. The air-trap intake port 503 is smoothed to the inside wall of theair-trap and is positioned off of the mid-line of the long axis of theair-trap. This position of the air-trap intake port 503, relative to themid-line of the long axis of the air-trap, causes the fluid beingintroduced to the air-trap to flow about the cylindrical form of theair-trap in a clockwise direction as the fluid fills and continues toenter the air-trap. This flow pattern creates a vortex within theair-trap, pulling air downward toward the fluid output port 505. At thebottom 502 of the air-trap there is located a flow disrupter 601, whichis positioned adjacent to the fluid output port 505. The flow disrupter601 can extend from the inner wall of the air-trap or the inner wall ofthe bottom 502 of the air-trap. As the fluid, which is travelingclockwise about the air-trap, flows across the flow disrupter 601, adifferential in pressure at the fluid output port 505 is created,drawing the liquid out of the air-trap and allowing the air or gasbubbles to flow upward along the long-axis of the air-trap.

Returning to FIG. 5, the level of fluid within the air-trap 110 iscontinuously monitored while the infusion device is being operated. Theair-trap 110 includes one or more sensor interfaces for communicationwith one or more sensors on the pump housing. For example, the air-trapmay include a lower level sensor interface 506 and an upper level sensorinterface 507. These two sensor interfaces communicate with a lowerlevel sensor 245 and an upper level sensor 246, as shown and describedin reference to FIG. 2d . When the level of fluid in the air-trap 110drops below one or more of the sensors, for example, below both theupper level sensor interface 507 and the lower level sensor interface506, a flow limiting mechanism, such as a tubing pinch clamp located ator about the fluid output port 505 closes. At approximately the sametime that the flow limiting mechanism located at or about the fluidoutput port 505 closes, a flow limiting mechanism located at or aboutthe air output port 504 opens. With the fluid output port 505 closed,fluid entering the air-trap 110 forces any air present in the air-trap,up the long axis of the air-trap. Because the air output port 504 isopen, any air within the air-trap is forced out of the air-trap and intothe air output tube 108 shown in FIG. 1. When the level of fluid in theair-trap 110 rises above the upper level sensor interface 507, the flowlimiting mechanism at the air output port 504 closes. At approximatelythe same time that the flow limiting mechanism at the air output port504 closes, the flow limiting mechanism at the fluid output port 505opens again. With the fluid output port 505 open, fluid flow out to thepatient via the primary outflow tube 111 is restored. The flow limitingmechanisms at or about each of the fluid output port and the air outputport are further described as a fluid outflow flow limiting mechanism240 and an air output flow limiting mechanism 241, respectively, inreference to FIG. 2 d.

The air-trap embodied by the present invention is capable of functioningat varying inclinations and orientations. The cylinder formed by theair-trap is between 3 inches and 10 inches in height, preferably between3.5 inches and 7 inches, and most preferably between 4 inches and 6inches. The diameter of the air-trap cylinder is between 0.5 inches and2 inches, preferably 0.625 inches and 1.5 inches, and most preferably0.75 inches and 1.25 inches. The air-trap is able to properly remove airfrom the fluid as it passes through, even when the air-trap is tiltedoff its vertical axis between 10° and 90°, though most preferably up to45°.

Heat Exchanger and Heating and Cooling Elements

As discussed above, efficient transfer of heat, to or from the infusionfluid, to be warmed or cooled impacts the present invention. Heatinginfusion fluid is first described, followed by illustrative examples ofcooling infusion fluid. It is appreciated that where heating by theheating element is described, a cooling element may alternatively beused to cool infusion fluid in a similar manner. The present invention'suse of a wide flow, short linear travel flow pattern allows for a moreturbulent flow with an extremely large contact area. The contact areabeing described is the area of interface between the heat exchanger andthe fluid passing through. Described as a ribbon of fluid, the fluidtraveling through a heat exchanger, made in accordance with the presentinvention, will flow in very short linear distances along the shortsegments of linear distance, but will instead be proportionately wider.In fact, the flow cavity created for fluid flow through the heatexchanger is wider than it is long, and longer than it is deep, therebycreating a tortuous ribbon shape for the fluid to pass through. FIG. 7is a representation of the fluid flowing through the heat exchanger 101.The fluid flow of FIG. 7 first is shown as having filled the exchangerinlet port as the inlet fluid 701. The fluid then fills the flow cavityas cavity fluid 702. The fluid then flows up the heat exchanger, firstthrough the smaller gap created by the flow fin indicated as the firstrestricted flow 703. It should be noted that linear flow distance λ,defined by the height of the fins and representing the short segments offlow length, is less than the flow width ω. The ratio between the linearflow distance λ and the flow width ω can be from about 1:2 to 1:50,preferably from 1:4 to 1:25, and most preferably from 1:5 to 1:10. It isthe ratio between the linear flow distance and the flow width whichcreates the ribbon-like flow pattern depicted in FIG. 7. By having sucha short linear flow, the fluid flows through the heat exchanger withmore turbulence than a typical long linear flow serpentine path. Theintroduction of turbulence in the fluid avoids the laminar type flowthat such a serpentine flow path may create. As opposed to merely themolecules within the central portion of the fluid flow, that is thosemolecules not located directed at the interface, changing over fasterthan the molecules at the interface, the turbulent flow created by thepresent invention exposes more fluid molecules to the interface, whichallows for an enhanced heat transfer. Likewise, this turbulent flowcreates more contact between the molecules within the fluid flowingthrough the heat exchanger. With more contact between the moleculeswithin the fluid, more heat exchange and transfer can occur, driving theefficient exchange of heat to or from the exchanger to the fluid to bedelivered to the patient.

A heat exchanger made in accordance with the present invention createsthis turbulent flow path and maintains it as the fluid flows over thefins. The fins 302, as depicted in FIG. 3, create one-half of the flowpath for the fluid to follow. The fins on the same side of the heatexchanger are evenly sized and spaced, that is the distance between afirst fin 307 and a second fin 308 is the same across the overall spanof the heat exchanger. For the purposes of heat transfer involving afluid flowing in the heat exchanger, the distance between a first andsecond fin of the same plurality of fins can be from 0.25 inches to 0.5inches, preferably from 0.35 inches to 0.45 inches, and most preferablyfrom 0.37 inches to 0.43 inches. The length of the fins on one-half ofthe heat exchanger dictates the linear flow distance. The length of thefins can be from about 0.25 inches to 1.0 inches, preferably from 0.5inches to 0.8 inches, and most preferably from 0.6 inches to 0.7 inches.The flow path also contains a depth element created by the separationdistance between the top of the fins in a first plurality of fins andthe valley between two fins in a second plurality of fins. The flow pathcan have a depth of about 0.01 inches to 0.25 inches, preferably 0.03inches to 0.125 inches, and most preferably 0.04 inches to 0.110 inches.The width of fins can be from 3 inches to 6 inches, preferably 3.5inches to 5 inches, and most preferably 4 inches to 4.5 inches. Again,it is appreciated that in other embodiments, however, the heat exchanger101 may provide a discrete flow path, such as a serpentine flow path,through which fluid may be directed.

For temperature control, transferring heat energy to or from the heatexchanger 101 occurs at an exposure surface 225 of the heat exchanger,the portion not covered or contained within the disposable cartridge, asshown in FIG. 2d , and from a thermal element contained within the pumphousing. The thermal element may be a heating element 810 or a coolingelement 850. The heating element 810 may be constructed as a powerresistor-based heating element, an inductor-based heating element, amicrowave-based heating element, radiant heating element, or the like,as is known in the art. The cooling element 850 may be a thermoelectriccooler, as is known in the art. Further, it is appreciated that acombination of one or more of the aforementioned thermal elements mayallow for selectively adjusting between heating or cooling capabilitiesin a single device.

The exposure surface 225 of the heat exchanger, visible in FIG. 2d , isexposed from the housing of the disposable cartridge 100. The disposablecartridge 100 is removably attached to the pump device via one or moreattachment points 210. The embodiment, as illustrated in FIG. 2d ,includes a first attachment point 210 and a second attachment point 210.The attachment regions allow the disposable cartridge 100 to be affixedto the pump housing 250 securely and tightly. It is important that theexposure surface 225 of the heat exchanger 101 be located as uniformlyclose to the heating platen 275 as possible. Even known smoothmaterials, when dealing with solids, are rarely completely in contactwhen considered at a microscopic level. Therefore, the exposure surface225 should be reasonably uniform and smooth in order to achieve as muchsurface area contacting the heating platen 275 as possible. The surfacearea of the exposure surface 225 which contacts the heating platen 275can be from about 20 square inches to about 100 square inches,preferably from about 25 square inches to about 50 square inches, andmost preferably from about 30 square inches to about 45 square inches.Likewise, the pressure exerted onto the disposable cartridge 100 to holdthe exposure surface 225 in close contact with the heating platen 275must increase if the surface of the exposure surface 225 and the heatingplaten 275 are not smooth. If the exposure surface 225 and the heatingplaten 275 are positioned immediately next to one another, it isconsidered that an air interface exists between the two surfaces. Whilethe surfaces will be extremely close and pressure will be exerted on theexposure surface 225 such to press the two surfaces together, gapsbetween the surfaces may remain. It is therefore possible to reducethese gaps by coating the heating platen 275 with a thermal pad 840,which conforms and fills the voids between the surfaces with a materialthat is a better heat conductor than air, yet allowing a reasonablecontact pressure to be used. If air serves as the interface between thesurface of the exposure surface 225 of the heat exchanger and theheating platen 275, then greater pressure must be exerted on the systemin order to achieve an efficient transfer of heat energy. Using amaterial that fills the gaps and is a better heat conductor than airallows the system to be established with a lesser and more reasonablepressure applied to the surface interface. Alternatively, the exposuresurface 225 may be coated with the thermal pad 840 to similarly fill thevoids caused by surface gaps. Furthermore, the compressive force exertedby engaging the engaging actuator and clamping mechanisms will furtherfacilitate the coupling of the exposure surface 225 with the heatingplaten 275. It is appreciated that for some thermal elements, forexample a heating element including a radiant heat source, a highpressure coupling of the exposure surface 225 with the heating platen275 is not as important as for the embodiment including a powerresistor-based heating element. Accordingly, less compressive force maybe applied.

It is appreciated that while a substantially flat exposure surface 225and a substantially flat heating platen 275 are described andillustrated in the figures herein, the exposure surface and the heatingplaten may be formed in other shapes. The exposure surface and theheating platen formed in other shapes, however, should still be formedso that the two are able to mate, so as to be positioned immediatelynext to on another and minimize the gaps between the two. Reasons forconfiguring the exposure surface 225 and the heating platen 275 in otherthan a substantially flat configuration may be for manufacturingefficiency, or to increase the exposure surface area, as well as forother reasons as are appreciated by those skilled in the art.

The disposable cartridge 100 may be removably attached to the pumphousing 250 by an engaging actuator 280, as depicted in FIG. 2c . Theengaging actuator 280 cooperates with one or more clamping mechanisms290 extending from one or more lock housings 285 located around theheating element 810. In one embodiment, the engaging actuator 280 may bea handle, constructed as a lever, as is shown in FIG. 2c . However, inother embodiments, the engaging actuator 280 may be a knob, anelectromechanical activated mechanism, or the like, as is known in theart. When the engaging actuator 280 is manipulated, the clampingmechanisms 290 extend from the pump housing 250 and may engage thedisposable cartridge 100 at attachment points 210. In one embodiment,the clamping mechanisms 290 may be constructed like a bail and theattachment points 210 may be constructed like brackets having a lippededge that extend away from the exposure surface 225. In this embodiment,the clamping mechanisms 290 may have an interior space that may engagethe bracket shape of the attachment points 210 and secure the disposablecartridge 100 to the pump housing 250. Though, it is appreciated thatother attaching means that may cause the disposable cartridge 100 to bereleaseably secured to the pump housing 250 as are commonly known in theart. When engaged, the engaging actuator 280 may cause compressive forceof approximately 100 pounds to 500 pounds, preferably about 200 poundsto 300 pounds, most preferably about 250 pounds, to be distributedacross the surfaces of the heating platen 275 and the exposure surface225. As described above, the compressive force created by the engagingactuator 280 facilitates mating of the two surfaces and improves heattransfer between the heating platen 275 and the exposure surface 225.Further, when the disposable cartridge 100 is fully engaged with thepump housing 250, by way of the clamping mechanisms 290, safetyinterlocks may be activated so as to signal that it is acceptable tobegin operation. Some advantages that the clamping mechanisms 290 andthe engaging actuator 280 have over the prior systems used for couplingtwo components, such as pneumatically engaged pistons or two-sided clamshells, are their ease of use, lighter weight and smaller sizes. Ascompared to previous pneumatic systems, the clamping mechanisms of thepresent invention generally require less force, and can be engaged by anoperator using only a single hand. Additionally, after aligning thedisposable cartridge with the pump housing, the disposable cartridge maybe loosely secured to the pump housing, so as to allow the operator tolet go of the disposable cartridge before finally engaging the engagingactuator. It is appreciated that in other embodiments, the engagingactuator need not create as much as 100 pounds of compressive force. Forexample, as stated previously, for an embodiment having a radiant heatsource for the thermal element, high-pressure coupling is not asnecessary. In an embodiment such as that, only enough compressive forceas is required to properly align, mate, and engage the sensors withtheir respective interfaces and/or receptors is necessary.

In one embodiment, the thermal element may be a heating element 810 asdescribed in FIG. 8a . The heating element 810 generates heat energyfrom multiple power resistors 830 indirectly communicating with theheating platen 275. The power resistors 830 may directly communicatewith one or more power insulators 820, which mate with the heatingplaten 275. The power insulator or insulators 820 may be constructed ofaluminum oxide having a thermal conductivity of about 20 W/m-K orgreater, and preferably about 30 W/m-K or greater, or other materialsknown in the art to have similar thermal conductance properties. Thepower insulators isolate the resistive load power from the heatexchanger 101 while still allowing efficient heat transfer and sinkingproperties to transfer heat to and from the heating element 810.Additionally, in one embodiment, thermal grease or thermal bondingcompound, as is known in the art, having nominal thermal conductivity ofabout 5 W/m-K or greater, preferably between about 8 W/m-K and about 10W/m-K, may be interposed between the heating platen 275 and the powerinsulators 820, and between the power insulators 820 and the powerresistors 830. Alternatively, however, the power resistors 830 may beprinted or deposited directly onto the power insulator 820, as is knownin the art. The specific embodiment illustrated in FIG. 8a shows eachpower resistor 830 in communication with individual power insulators820, which are in communication with the heating platen 275.

The resistors 830 are preferably connected, so as to limit the amount ofcapacitive coupling or capacitance leakage that occurs. Limitingcapacitive coupling is beneficial because it reduces current leakagebetween the heating element 810 and the heat exchanger 101, and thus theinfusion fluid, reducing the risk of causing electric shock to thepatient. In a preferred embodiment, capacitance leakage for the pumpdevice is less than 100 picofarads, and current leakage from the pumpdevice to the patient is less than 10 microamperes, and from the pumpdevice to a ground is less than 100 microamperes. Capacitive couplingmay be reduced by creating multiple heat points, instead of a singleheat point on the heating platen 275. In one exemplary embodiment, shownin FIG. 9, although any number of resistors 830 in any configuration maybe employed, five power resistors 830 connected in parallel, each havinga resistance of about 40 ohms to about 60 ohms, and preferably about 50ohms, may be connected such that three power resistors 830 create threeheat points on the lower portion of the heating platen 275 and two powerresistors 830 create two heat points on the upper portion of the heatingplaten 275. In the preferred embodiment between three to five, mostpreferably five, power resistors may create heat points on the heatingelement. It is appreciated that other circuit designs may be employedthat create about 10 ohms of total resistance and produce multiple heatpoints on the heating element, while still limiting capacitance leakageto about 100 picofarads, current leakage to the patient to about 10microamperes, and current leakage to the ground to about 100microamperes. The heating element 810 of this embodiment may beconfigured so as to heat the fluid between about 35° Celsius to about50° Celsius. In some embodiments, the heating element 810 may heat thefluid from about 37° Celsius to about 43° Celsius.

The heating platen may be constructed from aluminum alloys because theyare lightweight and have high thermal conductivity. It is appreciatedthat other materials, known in the art as having similar mass andconductivity properties, may also be used to construct the heatingplaten. For example, the heating element may also be constructed fromcopper, gold, silver, carbon, ceramics, or the like, as is known in theart. Further, it may be preferred to harden the aluminum alloy of theheating platen to prevent substantial yielding that may result from thecompressive force exerted during clamping the disposable cartridge tothe pump housing.

In an alternative embodiment, such as that shown in FIG. 8b , thethermal element may be a cooling element 850, instead of the heatingelement, to cool fluid before delivery to a patient. The cooling element850 may include the same heating platen 275 as is included in theheating element. It may further be constructed from one or morethermoelectric coolers 860, as are known in the art, mated against theheating platen 275. It is appreciated that in an embodiment includingthermoelectric coolers 860, capacitance leakage and current leakage maybe limited as described above in reference to FIG. 8a . Additionally,the cooling element 850 may have thermal grease or thermal bondingcompound interposed between the heating element 275 and thethermoelectric coolers 860, like that described above in reference tothe heating element 810. The thermoelectric coolers 860 may, by way ofheat transfer from the heat exchanger through the thermoelectric coolers860, create one or more cooled points on the heating platen 275. Coolingthe heating platen 275 to a temperature below that of the heat exchanger101 allows heat energy to transfer from the heat exchanger to thecooling element 850, and effectively lowers the temperature of the fluidcirculating through the heat exchanger 101. The cooling element 850 maypreferably be controlled using pulse-width modulation (PWM) to vary thepower supply voltage to each of the thermoelectric coolers 860.

The thermoelectric cooler 860 may preferably be a peltier device orpeltier thermoelectric cooler, as is known in the art. A peltierthermoelectric cooler 860, as may be used in the present invention,preferably includes an array of n-type and p-type semiconductorsinterposed between two ceramic insulators. The n-type and p-typesemiconductors may be n-doped bismuth telluride and p-doped bismuthtelluride pellets, respectively, or the like, as is known in the art.The thermoelectric cooler may also include a heat sink on the sideopposite that interfacing with the heating platen 275, so as toefficiently remove heat from the heating platen and the cooling side ofthe thermoelectric cooler 860. The cooling element 850 in thisembodiment may be used to cool infusion fluid to temperatures in theranges between about 0° Celsius to about 37° Celsius, more specificallyto about 4° Celsius to about 25° Celsius.

It is further appreciated that an embodiment that includes athermoelectric cooler 860 configured as a peltier device, as describedherein, may be used as a thermoelectric heat pump, so as to create aheating and cooling element. An embodiment configured in this manner, soas to include a heating and cooling element, allows for selectivelyheating or cooling the heat exchanger on the heat pump. As is known inthe art, a peltier device can be configured to source heat, when currentflows in one direction, and sink heat, when current is reversed in theopposite direction. Accordingly, a pump device configured in this mannermay allow for using a single device to selectively heat or cool fluid asdesired by the user.

In another embodiment including a thermoelectric cooler 860, thethermoelectric cooler may act as a thermoelectric heat pump, as is knownin the art, providing a heating and cooling element for the pump device.More specifically, a thermoelectric heat pump that is a peltier devicemay source or sink heat, depending upon the direction of the currentflow through the thermoelectric cooler. Accordingly, in an embodimentincluding a thermoelectric cooler/heat pump 860, the central controllermay be configured to allow the user to selectively control the currentflow through the heat pump, thus allowing the thermal element to createboth heat points and cooling points on the heating platen 275.

Dynamic Range Motor and Pump

The pump device includes a pumping mechanism that is driven by a dynamicrange motor drive assembly to pump the fluid from the fluid supply,through the heat exchanger, then to the patient. It is appreciated thatother aspects, described in the present application, may provideadditional functionality and paths through which the fluid may flowbetween the supply and the patient. The pumping mechanism may be aroller head occlusive pump. The rotating action of the pump roller headassembly imparts a directional, peristaltic motion to fluid existing inthe pump loop that is contained within the pump chamber. In otherembodiments, the pumping mechanism may be another type of peristalticpump, for example, a non-circular peristaltic pump, a centrifugal pump,an impeller, or the like, as is known in the art for pumping fluidsthrough malleable tubing. The motor drive assembly may be electronicallycontrolled, for example, by a digital signal processing controller (DSPcontroller), as further described herein. In one embodiment, the pumpingmechanism and motor drive assembly, in combination, are capable ofdelivering about 1 milliliter of fluid per hour to at least about 3000milliliters of fluid per minute. Though, in some embodiments, the pumpdevice may only be required to pump between 10 milliliters of fluid perhour to about 1200 milliliters of fluid per minute (e.g., during typicalblood replenishment or replacement procedures), while in otherembodiments the preferred range may be between 2000 milliliters and 8000milliliters of fluid per minute (e.g., for delivery during emergencyheart and lung procedures). In another embodiment, the pumping mechanismand the motor drive assembly are capable of maintaining delivery offluid at predetermined pressure ranging from about 0 mmHg to about 750mmHg.

A motor drive assembly may be used to drive the pumping mechanism shownin FIG. 10. The motor drive assembly may include a motor 1010, which maybe a DC motor, preferably a brushed DC motor, as is known in the art.One example of a brushed DC motor that may be used is Maxon MotorsRE-max motor (part no. 118751), rated at 20 Watts at a nominal voltageof 18 Volts DC and having a no-load speed capability of 10,200revolutions per minute. The motor drive assembly may also include a gearassembly 1030. The motor 1010 may communicate with the gear assembly1030 so as to scale the rotation speed of the motor to ranges acceptableby the pumping mechanism. The gear assembly, however, operates in astatic configuration, wherein the gear ratio is fixed and does notchange during operation. In a preferred embodiment, the gear assembly1030 may provide an approximate 14:1 gear ratio. It is appreciated thatother gear ratios may be used, depending upon the rotation speed of themotor used, the configuration of the electronic motor controller, andthe pumping mechanism requirements. One example of a gear assembly foruse in the present application is Maxon Motors Planetary Gearhead GP 26B (part no. 144029). The motor 1010 and gear assembly 1030 areintegrated within the pump housing 250. The motor 1010 is preferablyconnected to and controlled by an electronic controller. Additionally,the motor 1010 is connected to a power source to supply voltage acrossits terminals, as described below. It is appreciated that thecombination of the motor drive assembly and the electronic controllerallows for dynamically selecting wide flow ranges, for example, from 1milliliters per hour to 8000 milliliters per minute, with the use of asingle motor and without the further use of additional stepper motors ordifferential drives.

The motor 1010 and gear assembly 1030 communicate with the receiver ofthe pumping mechanism 1020. A coupler 1040 may be used to couple theoutput shaft of the gear assembly 1030 to the receiver of the pumpingmechanism 1020. In one embodiment, the pumping mechanism 1020 mayinclude a pumphead with multiple rollers, preferably three, thatsuccessively engage then release the tubing of the pump loop 104 withinthe pump chamber. Turning the roller heads and rollers causes occlusivepumping, as is known in the art.

The pump loop 104 preferably consists of at least one section ofcollapsible tubing, through which the fluid will flow upon initiation ofpumping action. The pump loop tubing may have a thinner wall than otherinfusion tubing, allowing for easier pumping action by the rollerpumphead. However, harmonics resulting from the pumping motion impartedon the pump loop tubing may cause fill and rebound cycles in the tubebehavior, and thus may cause variability in flow rates or flowpressures. Thus, it may be preferable to reduce the fill and reboundbehavior by controlling the length of the tubing in the pump loop 104,and thus the tension of the pump loop 104, when engaged with the pumpingmechanism. Controlling the tension of the pump loop 104 effectivelycreates a tube having a shorter, fixed length, thus producing flowbehavior more predictable than a tube having a greater length or avariable length. This may be accomplished by securing the tubing of thepump loop 104 at fixed points on the disposable cartridge, at a point orpoints before the portion of the tubing that engages the pump head, andat a point or points after the portion of the tubing that engages thepump head. In one embodiment, as illustrated in FIG. 1, the pump loop104 may be constructed from a different tubing having a different wallthickness than the primary inflow tube 102 and the pump outflow tube109. The pump loop 104 may be coupled, by methods known in the art, tothe primary inflow tube 102 and the pump outflow tube 109. Thus, theends of the pump loop 104 may be affixed to the disposable cartridge, soas to control its tension and tube length, where the pump loop 104couples with the primary inflow tube 102 and the pump outflow tube 109.In this embodiment, a tubing coupler 113 connecting the tubes may bepermanently affixed to the disposable cartridge, and the tubing endsslide thereover. Further, the tubing may be secured over the tubingcoupler 113 by methods known in the art, such as a self-tensioning clipsurrounding the tube ends over the tubing coupler 113. It is appreciatedthat other means of securing the ends of the pump loop 104 to thedisposable cartridge, as are known in the art, may be employed.Accordingly, in this embodiment, the tube tension and length through thepumphead may be advantageously controlled by affixing each end to thedisposable cartridge, so as to reduce variability in pressure and flowrates.

The Watson-Marlow 313D pumphead (part no. 033.3401.000) is an example ofa three-roller pumping mechanism, configured for use with tubing having1.6 millimeter walls, and for providing 3 milliliter per revolution flowrate. The Cole-Parmer peroxide-cured silicon tubing (part no.K-06411-71) is an example of tubing for use in the pump loop, having aninner diameter of 6.4 millimeters and a wall thickness of 1.6millimeters, that may be used with the pumping mechanism. It isappreciated that other pumping assemblies and tubing configurations, asare known in the art, may be used in embodiments of the presentinvention, such as two or four roller pumpheads or pumpheads,non-circular peristaltic pumps, centrifugal pumps, impellers, or thelike, as is known in the art. Additionally, the infusion tubing in thepump loop may be configured to have different tube bores and wallthicknesses. Alternative combinations of pumping mechanisms and tubingsizes will yield different flow rate ranges, as is known in the art.

The motor 1010 may be controlled by an electronic controller 1110 as isdescribed by the functional block diagram in FIG. 11. The electroniccontroller 1110 may be a DSP controller that receives a signal from theuser input control and converts it into a pulse-width modulation (PWM)signal that ultimately dictates the speed of the motor. A PWM signalcontrols the speed of the motor by signaling a maximum voltage, 10volts, for example, to be applied across the motor and a minimum voltageintermittently. The duration at which the voltage is fully on, referredto as the “duty cycle,” may be varied, which in turn varies the speed ofthe motor. A duty cycle of 100%, for example, would turn the motor atits maximum speed, because the voltage across the motor would always befully on; whereas a duty cycle of 75% will reduce the speed of themotor, because the time during which the max voltage is applied isdecreased. Preferably, the electronic controller 1110 is a highresolution DSP controller, preferably about a 16-bit to about a 64-bitprocessing controller, and more preferably about a 32-bit processingcontroller. The electronic controller 1110 may be integrated with motorpower drive circuitry 1120 to control the current flowing through themotor 1010, as is known in the art. A tachometer 1130, or an encoder,may be integrated within the system to sense the number of revolutionsat the motor and provide feedback to the electronic controller 1110 andthe device central controller 1100. The tachometer allows the electroniccontroller 1110 and the central controller to know the flow rate of thedevice, by sending information directly related to the number ofrevolutions over time, which is then used to calculate flow rates,because the flow rate per revolution is known based on the infusiontubing and pumphead configuration. The higher the tachometer'sresolution—the number of counts per revolution of the motor shaft—themore accurate the DSP controller will be during operation. In apreferred embodiment, the tachometer has between about 250 lines ofresolution to about 1000 lines of resolution, and more preferably, hasabout 500 lines of resolution. An example of an electronic DSPcontroller for use in an embodiment of the present invention, isNational Semiconductor Precision Motor Controller (part no. LM629M-8).The LM629M-8 is a 24-pin surface mount controller that has 32-bitregisters for velocity, position, and acceleration, and a programmableProportional Integral Derivative (PID) filter with 16-bit coefficientsto compensate for error, as detected in the feedback loop, as is knownin the art. The LM629M-8 can interface with the National Semiconductor 3A, 55 V, H-Bridge (part no. LMD18200), as power drive circuitry 1120, toreceive the PWM and direction signals from the LM629M-8 and drive themotor 1010, as is known in the art. It is appreciated that the motor maybe controlled by other means, such as a general-purpose computer havinga communication link to send and receive signals, a memory, andprogramming logic, or an analog controller, using resistive rheostat, orthe like, as is known in the art.

The dynamic range motor drive assembly and disposable cartridgecombination may provide flow rates of about 1 milliliter per hour to, atleast, about 4000 milliliters per minute to satisfy the infusion needsfrom the low flow needs of Keep Vein Open (KVO) state to the rapid, highflow infusion of crystalloid, colloid, or blood product, includingpacked red blood cells. Further, in other fluid delivery uses, asdescribed herein, the dynamic range motor drive assembly may provideflow rates between about 2000 milliliters per minute and 8000milliliters per minute. It is appreciated that the user input may beconfigured so as to allow adjusting the flow rate in slight increments,as well as to allow for rapid adjustment of the flow rate. It ispreferable, however, that a single selection (e.g., pressing the ratebutton once) will increase (or decrease) the flow rate by anywhere fromapproximately 5 milliliters to approximately 20 milliliters, and mostpreferably will increase (or decrease) the flow rate by approximately 10milliliters. The ability to provide and control this broad range of flowrates may also be advantageously employed for infusion normothermicfluids into patients after surgery, or for treating or preventinghypothermia. Examples of fluids that may be delivered by the device areblood, crystalloid, colloid, saline, medication, any combinationthereof, or the like, as is known in the art. Yet another beneficial useof a broad spectrum of flow rates is the high speed delivery ofirrigation fluids which may be warmed.

The dynamic range motor drive assembly may be further configured todeliver fluid at a substantially constant infusion pressure, which maybe predetermined by the user between about 0 mmHg and about 750 mmHg,and preferably between about 25 mmHg and about 150 mmHg. Morespecifically, the user input may be configured to allow the user toselect the preferred pressure around which the delivery should bemaintained. For example, the user may select to infuse fluid at aconstant pressure of 45 mmHg, causing the central controller to signalto the dynamic range motor drive assembly to increase the fluid flowrate until 45 mmHg of pressure is achieved. After achieving thepredetermined 45 mmHg of pressure (in this example), the motor and pumpmechanism may slow, so as to reduce the fluid flow, in an effort tosubstantially maintain the predetermined pressure. When, however, theone or more pressure sensors sense that the pressure is falling belowthe predetermined pressure, the central controller will cause the motorand pump mechanism to increase the flow rate, so as to increase thepressure, until it reaches the predetermined pressure again.Accordingly, by making adjustments to the flow rate, the pump device isable to maintain a substantially constant pressure. It is appreciatedthat the adjustments to the flow rates may be minor adjustments, forexample, 5-25 milliliters per minute, or may be more drasticadjustments, such as stopping flow altogether (i.e., 0 milliliters perminute). Pressure sensors contained in the disposable cartridge, such asthe outflow pressure sensor, provide feedback to the control unit forproper adjustment of the DSP controller to maintain a constant pressure.

Attachment and Alignment

The components of the disposable cartridge that interface with the pumphousing are advantageously arranged and designed, so as to allow simple,one-step attachment of the exchanger. FIG. 2d illustrates the alignmentof the corresponding elements between the disposable cartridge 100 andthe pump housing 250.

As described above, the exposure surface 225 of the heat exchanger 101preferably mate with the heating platen 275 on the pump housing 250, soas to promote heat transfer by creating minimal air gaps between the twoelements. Additionally each sensor located on the pump housing alignsand communicates with its corresponding mate on the disposable. Theremay also be an alignment mechanism, such as one or more guide pins 282on the pump housing and corresponding guide receptors 284 on thedisposable cartridge, to facilitate proper alignment when attaching thedisposable cartridge to the pump housing. Proper mating also allows theheat exchanger temperature sensor 287 to communicate with, andaccurately measure, the heat exchanger 101 temperature.

The disposable cartridge 100 may include one or more detector interfaces230, allowing one or more sensors on the pump housing to correspondinglycommunicate with the infusion tubing on the cartridge. For example, afirst detector interface 230 may allow the inflow bubble detector 120and the inflow temperature sensor 260 to communicate with the infusiontubing 102, and the second detector interface 230 may allow the outflowbubble detector 112 and the outflow temperature sensor 261 tocommunicate with the outflow tubing 111 upon attaching the disposablecartridge to the pump housing. In one embodiment, as illustrated in FIG.2d , the detector interfaces 230 may be formed as apertures and sensorson the pump housing, for example, the bubble detectors 120, 112, and thetemperature sensors 260, 261, may extend therethrough to communicatewith the infusion tubing contained inside the cartridge. Alternatively,in another embodiment, the side of the disposable cartridge interfacingwith the pump housing may not include an exterior casing, leaving theinfusion tubing exposed. In this embodiment, the detector interfaces 230are simply the portions of the exposed infusion tubing that communicatewith the sensors on the pump housing. The inflow and outflow bubbledetectors 120, 112 may be ultrasonic sensors that are positioned withinan open-ended, c-shaped, clamp-like receptacle that receives theinfusion tubing and positions the ultrasonic sensors in close proximityto the tubing when in place. In other embodiments, the bubble detectors120, 112 may be optical-based sensors, such as laser sensors usingDoppler based calculations, or the like, as is known in the art.Similarly, the inflow and outflow temperature sensors 260, 261, whichmay be infrared sensors, are positioned within a similar open-ended,c-shaped, clamp-like receptacle, so as to be in close proximity to thetubing when in place. In other embodiments, the temperature sensors 260,261 may be optical-based sensors, such as laser sensors, mechanicalthermistors, or the like, as is known in the art.

Additionally, the primary inflow tube 102 and the primary outflow tube111 may be lubricated, formed from a lubricious material, or thereceptacles on the pump housing may be lubricated, so as to facilitatethe mating between the infusion tubing and the inflow and outflow bubbledetectors 120, 112 and the inflow and outflow temperature sensors 260,261. Alternatively, the inflow and outflow temperature sensors 260, 261and the inflow and outflow bubble detectors 120, 112 may be lubricatedon their interior surfaces that engage and mate with the infusiontubing. The lubricant may be a heat resistant compound, such assilicone, or the like, as is known in the art. Furthermore, an energytransmitting material may be applied to either the infusion tubingand/or the bubble detectors 120, 112 and the temperature sensors 260,261 to facilitate the transmission of energy from the sensor to theinfusion tubing and fluid contained therein. For example, forultrasonic-based sensors, a silicone based material may be used tofacilitate transmission of sound energy. Alternatively, when includinglaser-based sensors, a non-refractive material may be used to facilitatethe transmission of light energy.

The disposable cartridge may include one or more flow limitinginterfaces 235 that align with one or more flow limiting mechanisms,which are used to restrict the flow of air or fluid through the infusiontubing at the position of the one or more flow limiting interfaces. Forexample, two flow limiting interfaces 235 may be formed as apertures onthe disposable cartridge 100 and may allow for the fluid outflow flowlimiting mechanism 240 and the air output flow limiting mechanism 241 toextend therethrough and engage the outflow tubing 111 and the air outputtubing 108, shown in FIG. 1, so as to allow for preventing the flowthrough the respective tubing when engaged. The tubing flow limitingmechanisms 240, 241 may be solenoid activated clamps that, whenactivated, are retracted substantially within the pump housing, and,when deactivated, extend outwardly, engage the infusion tubing, andcompress the tube to effectively prevent the flow. Flat surfaces may bealigned behind the infusion tubing within the disposable cartridge 100to receive the infusion tubing as it is compressed by the tubing flowlimiting mechanisms. Alternatively, in another embodiment, the side ofthe disposable cartridge interfacing with the pump housing may notinclude an exterior casing, leaving the infusion tubing exposed. In thisembodiment, the flow limiting interfaces 235 are simply the portions ofthe exposed infusion tubing that communicate with the fluid outflow andair output flow limiting mechanisms 240, 241.

There may be one or more pressure sensors on the pump housing thatcommunicate with pressure receptors on the disposable cartridge. In oneembodiment, an inflow pressure sensor 270, a pump outflow pressuresensor 271, and a fluid outflow pressure sensor 272 extend through aninflow receptor 295, a pump outflow receptor 296, and a fluid outflowreceptor 297, respectively. The pressure sensors may be, in oneembodiment, sensor needles, and the pressure receptors may be orificesthat receive the sensor needles. Upon attachment, the pressure sensors270, 271, 272, by way of the pressure receptors 295, 296, 297, are incommunication with the inflow, pump outflow, and fluid outflow pressurejunctions 103, 105, 135 of the disposable cartridge. By extending intothe pressure receptors 295, 296, 297, the pressure sensors 270, 271, 272may open a check valve therein and communicate with a captured volume ofgas (e.g., the first air chamber 151) between the pressure sensor andthe fluid flowing through the infusion tubing, whereby the pressure ofthe captured volume of gas is directly related to the fluid pressure inthe associated infusion tubing. This pressure may be sensed by pressuretransducers in the pump housing in communication with each of thepressure sensors. In the embodiment, the pressure receptors may extendfrom the disposable cartridge and have an orifice, approximately thesame, or preferably a slightly smaller, diameter as the outer diameterof the pressure sensors, through which the pressure sensors extend. Thepressure receptors may be constructed from a polymer material that ispliable, so as to provide a tight seal around the pressure sensors, suchas silicone, a silicone compound, or the like, as is known in the art.Further, in this embodiment, each pressure receptor may include a collar292 extending from the disposable cartridge and surround the outsidediameter of each of the pressure receptors. The collars 292 may beconstructed from a hard material, such as a plastic, a metal, acomposite, or the like, and may preferably be constructed from the samematerial as the cartridge from where the collars 292 extend. The collars292 are included to prevent deformation of the pressure receptors, andto prevent the pressure receptors from separating from the pressuresensors when under high pressures, thereby allowing for continuedaccurate pressure monitoring. It is appreciated that, in otherembodiments, the pressure sensors may not have a needle configuration,thus there may be no need for the receptors to have an orifice.Accordingly, the pressure sensors, described herein, are exemplary, andany other pressure sensors, as are known in the art, may be used.

There may be one or more sensors on the pump housing 250 that may alignwith one or more points on the air-trap. These sensors may detect thefluid level at the one or more points on the air-trap. The sensors maybe ultrasonic sensors, optical sensor, such as a laser, or the like, asis known in the art for detecting differences in material properties. Inone embodiment, the air-trap includes the lower level sensor interface506 and the upper level sensor interface 507, as described above, inreference to FIG. 5, and the pump housing 250 includes a lower levelultrasonic sensor 245 and an upper level ultrasonic sensor 246. Thelower and upper ultrasonic sensor interfaces 506, 507 utilize padsconstructed from a material favorable to transmitting energy, such assilicone, urethane, or the like, as is known in the art, to mate withthe lower and upper level ultrasonic sensors 245, 246. The pads of theultrasonic sensor interfaces 506, 507 provide a material that improvesthe signal responses of the ultrasonic sensors, in order to effectivelymeasure the level of fluid within the air-trap.

It is appreciated that the pump device and/or cartridge may containother sensing devices than those previously described. For example, oneor more blood sensors may be included on the pump housing to interfacewith one or more points on the infusion tubing, so as to monitorproperties of blood flowing therethrough. The blood sensor may be anoptical-based sensor, such as a raman laser, or the like, as is known inthe art. The blood sensor may monitor blood properties or bloodchemistry such as, but not limited to: blood hematology, electrolytes,enzymes, blood gasses, clotting indices, and glucose levels. Other bloodchemistry characteristics may likewise be monitored or sensed, as isknown in the art. Another example of an additional sensor that may beincluded in the pump device is a flow sensor. The flow sensor may be anultrasonic sensor, an optical-based sensor, such as a laser sensor, athermal sensor, or the like, as is known in the art.

Accordingly, each of the components described above properly align andengage with the pump housing upon attachment. To align the disposablecartridge 100 to the pump housing 250, the clamping mechanisms 290 ofthe pump housing shall be aligned with the attachment points 210 on thedisposable. By aligning the clamping mechanisms 290 with the attachmentpoints 210, the individual components are directly aligned with theircomplimentary mate. Alignment mechanisms, such as the one or more guidepins 282 on the pump housing and the corresponding guide receptors 284on the disposable cartridge, may also be included to facilitate properalignment when attaching the disposable cartridge to the pump housing.The guide receptors 284 may be configured as apertures having a diametercorresponding to that of the one or more guide pins 282. Closing theengaging actuator 280 will cause the clamping mechanisms 290 to pull theattachment points 210, and therefore the disposable, to mate with thepump housing, and to interconnect each component pair. Furthermore, thepump housing 250 may include an install detector that determines whetherthe disposable cartridge 100 is properly aligned and attached. Theinstall detector may be one or more switches that are tripped uponsuccessfully attaching the disposable to the pump housing. The pumpdevice may be configured to generate an alert or an alarm if the userattempts to begin operation without the install detector being tripped,or it may alternatively be configured to not power on or begin pumpingunless the install detector has been properly tripped.

User Input and Control

The pump device allows user control through a simple user interface thatoffers easy access to primary functions by requiring minimal inputselections by a user. FIG. 12 shows an example of an user interfacepanel 1200 of the present invention. The user interface panel 1200preferably allows for only a single selection to cause the infusiondevice to perform time sensitive functions during operation. In aneffort to promote efficient operation and fast response operation,multi-level menus are minimized, if at all, to those functions that arenot time sensitive. Additionally, the device may be configured so as toallow the user to alter the operating states of the pump duringoperation, without having to halt the device and/or navigate throughmulti-level configuration or options menus.

Certain aspects of the present application reference block diagrams ofsystems, methods, and apparatuses, according to at least one embodimentdescribed herein. It will be understood that each block of the blockdiagrams, and combinations of blocks in the block diagrams,respectively, can be implemented, at least partially, by computerprogram instructions, generally referenced herein as the centralcontroller 1100. These computer program instructions may be loaded ontoa general purpose computer, special purpose computer, special purposehardware-based computer, or other programmable data processing apparatusto produce a machine, such that the instructions, which execute on thecomputer or other programmable data processing apparatus, create meansfor implementing the functionality of each block of the block diagrams,or combinations of blocks in the block diagrams, discussed in detail inthe descriptions below.

The user interface control panel 1200 may include power input 1210 thatturns the infusion device on, if it is not already on. If the device isalready on, selecting the power input 1210 may cause the machine to gointo standby mode if it is plugged in, or may turn off the infusiondevice if it is running on batteries or any other alternative powermeans. A prime input 1220 allows the user to select either manual prime,by continuously depressing the prime input 1220 for the duration forwhich priming is desired, or automatic prime, by selecting and releasingthe prime input 1220. More details regarding the prime sequences arediscussed below in reference to FIGS. 13-15. A heat input 1230 willallow the user to turn the heating element 810 on and off. In anotherembodiment, the user interface may include a cooling input in place of,or in addition to, the heat input 1230 that allows the user to turn thecooling element 850 on and off, if included in the device.

One or more maximum pressure inputs 1240 may allow the user to selectthe maximum pressure tolerated in the infusion tubing. For example, thepump device may include two maximum pressure inputs 1240, such as 100mmHg and 300 mmHg, and if one or more of the pressure sensors sense apressure exceeding the pressure level corresponding to the maximumpressure input 1240 selected, the device may reduce the flow rate, orstop pumping fluid and alert the user of the excessive pressure in thesystem. For example, during operation, if a flow rate of 500 millilitersper minute and a maximum of 100 mmHg is selected, the device willincrease the flow rate until 500 milliliters per minute is achieved,unless the pressure reaches or exceeds 100 mmHg. If the pressure reachesor exceeds the selected limit, the device will slow the flow rate so asto allow the pressure to drop. After the pressure drops, the device willincrease the flow rate again until the flow rate is reached, repeatingthe cycle until the selected flow rate is achieved without exceeding thepressure maximum. Similarly, the pump device may include a pressureincrease input 1242 and a pressure decrease input 1244, by which theuser may pre-define a pressure to be maintained by the pump device. Thepump device may further include one or more preset pressure inputs,which will allow the device to maintain the flow pressure correspondingto the pressure preset selected. The pressure maintenance level may bedisplayed in a selected pressure indicator 1246. An actual pressureindicator 1248 may display the actual pressure during operation. Usingthe pressure increase input 1242 and the pressure decrease input 1244will allow the device to pump fluid at a substantially constantpressure. For example, the infusion device may pump fluids maintainingthe pressure between a range of about 0 mmHg and about 750 mmHg, andmore preferably between about 25 mmHg and about 150 mmHg. For example,the user may select the pressure increase input 1242 until 45 mmHg isdisplayed in the selected pressure input 1246. During operation in thisexample, the dynamic range motor drive assembly will adjust the fluidflow rate to maintain, within a reasonable tolerance, for example,within 5%-20% of the selected pressure, a 45 mmHg pressure reading atthe outflow pressure sensor.

A standard infusion input 1250, a rapid infusion input 1260, and a groupof bolus preset inputs 1270 allow a user to select the infusion mode ofthe device. Selecting the standard infusion input 1250 will cause thedevice to pump fluid at a predetermined rate. For example, the devicemay, by default, pump 120 milliliters per hour when the standardinfusion input 1250 is depressed. Similarly, selecting the rapidinfusion input 1260 may cause the device to pump at a predetermined ratefaster than the standard infusion, for example 500 milliliters perminute. The bolus preset inputs 1270 may include one or more buttonsthat, when selected, cause the infusion device to deliver apredetermined volume, for example, 100, 250, 500, or 1000 milliliters,of fluid at a predetermined rate, for example, at 500 milliliters perminute. The predetermined rate for each of the standard, rapid, andbolus infusion modes may be altered by the user by depressing the rateincrease input 1280 or rate decrease input 1281. The rate increase anddecrease inputs 1280, 1281 preferably only cause a small increment ordecrement in the infusion rates, for example, between approximately 1milliliter and 50 milliliters, preferably approximately 10 milliliters,each time the buttons are depressed. This allows a simple, but precise,control over the flow rates. Additionally, it may be preferable to alsoallow for a rapid rate increment or decrement when the rate increase anddecrease inputs 1280, 1281 are depressed and held. For example, if therate increase input 1280 is held, the infusion rate may increase betweenapproximately 10 and 500 milliliter increments or decrements, preferablyapproximately 50 milliliter increments, instead of 5 or 10 milliliters.

Depressing the start input 1285 will cause the pump device to beginoperation in the selected mode. Similarly, the stop input 1286 willcause the pump device to stop delivering fluid. Additionally, it may beadvantageous that the operation of the device, and the signals beingsent from the above-discussed sensors, can be monitored so as to haltoperation while unwanted behavior is encountered. For example, if theoutflow bubble detector 112 senses air in the infusion tubing, a signalshould be sent to the central controller to halt operation and signal tothe user the nature of the problem encountered. Another example would bethe outflow temperature sensor 140 detecting temperatures less than thedesired temperature, thus causing the central controller to stopinfusion and alert the user as to an error with the heat exchanger.Other examples of operating behavior that may cause an alarm and/or haltthe device operation are, but not limited to: battery levels, excessivevolume infused, motor failure, disposable not properly attached,pressure failures, computer/control unit failure, infusion lineocclusion, and pump failure. It should be appreciated that the foregoingexamples are for illustrative purposes, and that many other sensors anderror handling routines may be implemented in the present invention, soas to at least cause a signal to be sent to the user and possibly tohalt the operation of the device.

The user interface control panel 1200 may also cause indicators to bedisplayed showing the state in which the pump device is operating andcertain selected parameters. For example, LED indicators may be matedwith each of the above exemplary input options, so as to indicate whichinputs have been selected. This gives the user a quick indication of thestate in which pump device is operating. Additionally, there may be aselected rate indicator 1290, an actual rate indicator 1291, a selectedpressure indicator 1246, and an actual pressure indicator 1248 thatdisplay to the user the flow rate and pressure selected by the user, andthe actual flow rate and pressure of the device, respectively. Thesedisplays may be LED indicators, liquid crystal display indicators, orthe like, as is known in the art. It is appreciated that other alertingmechanisms, such as beeps, alarms, tones, verbal warnings, or the like,as is known in the art, may be used by the present invention to indicatecertain conditions and the severity thereof.

There may optionally be another status display panel 1205, in which thecurrent operating data and any existing alarm indicators may bedisplayed, as also shown in FIG. 12. In this embodiment, the statusdisplay panel 1205 displays seven lines to the user in real-time. Thepanel may be constructed of a vacuum fluorescent display, liquid crystaldisplay, or the like, as is known in the art. The status display panel1205 may indicate, among others, the infusion mode selected, the heaterstatus, the fluid temperature, the fluid pressure, the total amount offluid infused, remaining volume and time for bolus infusion, and alarmsor warning messages. It is appreciated that the aforementioned statusesare exemplary, and other statuses may be signaled to the user in thestatus display panel 1205.

FIG. 13 provides a flowchart illustrating exemplary steps required foroperation of the present invention. First, the pump may be turned onusing the user interface control panel, as shown at block 1310. Afterturning on, the disposable cartridge is aligned with the pump housingand attached by engaging the engaging actuator, shown at block 1320. Thepump device may be configured so certain functions are automaticallyactivated upon attaching the disposable cartridge to the pump housing.For example, the device may default to a heating mode whereby theheating element is activated upon attaching the disposable. Block 1330shows that before operation, the pump is preferably primed, so as toremove any air from the infusion tubing prior to delivery to thepatient. The pump may be manually primed or may be automatically primed,as is illustrated in FIGS. 14-15. After priming, the pump may beoperated in standard, rapid, or bolus infusion modes, as at blocks1340-1350. Alternatively, the pump may be operated in a pre-selectedpressure maintenance mode (not shown). As described above, the flowrates in each of these modes may preferably have a preset flow rateassociated with it, but allow for changing the preset to a desired flowrate. Finally, the pump may stop pumping, as in block 1360, because of,among other reasons, the desired volume has been infused, an error onthe device, or the stop input button is depressed.

Before entering into an infusion mode, the pump device is preferablyprimed. The pump device may be primed either automatically or manually.FIG. 14 shows exemplary steps that may be executed during automaticpriming. After the device is on, in block 1410, depressing and releasingthe prime input 1220 will cause the pump device to begin primingautomatically, as is shown in blocks 1420-1430. Automatic priming mayinclude two stages, a first stage, shown in blocks 1440-1450, duringwhich fluid is pumped through the device until it reaches the lowerlevel sensor of the air-trap, and a second stage, during which fluid ispumped at a greater rate, shown in blocks 1460-1470. The first stage maypump the fluid at a predefined rate, for example, between approximately10 milliliters and 900 milliliters per minute, and preferably 500milliliters per minute. The second stage may pump at a predefined rate,for example, between approximately 900 milliliters and 1200 millilitersper minute, and preferably 1000 milliliters per minute. The second stagemay begin after fluid is detected by the lower level sensor, in block1450, and continue until between approximately 10 milliliters and 100milliliters, for example, about 35 milliliters, of fluid has been pumpedafter air purging through the air-trap is complete, as shown in blocks1480-1490. If automatic priming is not complete in a predeterminedperiod of time, for example ten minutes, an error shall be generated andthe device shall stop priming, as is shown in blocks 1495-1496.Additionally, it is preferable that once a disposable has gone throughautomatic priming it does not go through automatic priming again.

FIG. 15 shows exemplary steps that may be executed during manualpriming. After the pump is on, at block 1510, manual priming may beinitiated by depressing and holding the prime input 1220, illustrated byblocks 1520-1530. While depressing the prime input 1220, the device maybegin to fill the disposable at a predefined rate, for example, betweenabout 10 milliliters per minute and about 1200 milliliters per minute,and preferably about 500 milliliters per minute, as is shown in block1540. Block 1550 illustrates that the device will continue to primemanually until the user releases the prime input 1220. Upon release ofthe prime input 1220, the device will stop pumping, as shown in block1560. After the device has been properly primed, it may begin infusion,as described above.

FIG. 16 shows exemplary steps that may be executed for controlling thethermal element, for example the heating element 810 or the coolingelement 850, for warming or cooling the infusion fluid to the desiredtemperature. As noted above, heating or cooling a fluid within the heatexchanger is a function of the difference in mass between the fluid andthe surrounding heat exchanger, the thermal conductivity of the fluid,the nature of the turbulence (mixing) of the fluid within the heatexchanger, the temperature differences between the heat exchanger andthe fluid, and the duration of the fluid's presence within the heatexchanger.

The pump device operates to maintain the heat exchanger at apredetermined temperature, which may be sensed by the heat exchangertemperature sensor 287, as shown in block 1610, and further described inreference to FIG. 2d . Alternatively, the inflow temperature sensor 260or the outflow temperature sensor 261 may sense the fluid temperatureand be used, at least partially, to determine the thermal elementoperation. The central controller 1100 provides power to the heatingelement 810 or to the cooling element 850, as necessary, within theoperating and safety limits of the device, to achieve a predeterminedtemperature. As a consequence of seeking the predetermined temperature,power is applied to the heating element 810 or cooling element 850, asis needed, raising or lowering the temperature of the heat exchanger101, as shown in block 1640, and thus raising the temperature of a coolfluid passing through the heat exchanger 101, or lowering thetemperature of a warm fluid. For example when warming fluid, at a givenflow rate, say 200 ml/min, a colder fluid will take more energy out ofthe heat exchanger than a warm fluid when achieving an equilibriumtemperature. Thus, the more heat transferred to the fluid, the less heatin the heat exchanger, resulting in a lower temperature reading at theheat exchanger temperature sensor, and requiring more power to beapplied to the heating element to hold the predetermined temperature.The device operates similarly when cooling fluid by the heat exchangerusing a cooling element—when the heat exchanger temperature sensormeasures a greater temperature than the predetermined temperature, thenpower is applied to the cooling element to further cool the heatexchanger, drawing heat from the fluid therein.

In addition to maintaining the heat exchanger at the predeterminedtemperature, the central controller also takes into consideration theflow rate. At block 1620, the central controller receives the calculatedflow rate of the infusion fluid from the dynamic range motor driveassembly, as further discussed in reference to FIGS. 10-11. Consideringthe flow rates allows compensating for any inherent lag in the systemdue to the mass of the heat exchanger and the speed of the reaction ofthe designed circuit.

At block 1630, the central controller receives from the inflowtemperature sensor 260, as further discussed in reference to FIG. 2d ,the temperature of the fluid prior to entering the heat exchanger.Considering the temperature of the fluid before heating or coolingallows compensating for the greater heat energy transfer requiredbetween the heat exchanger and the fluid during warming or cooling.

Thus, as occurs at block 1640, the central controller may consider atleast one or a combination of the heat exchanger temperature, the inflowtemperature, and the flow rate to cause proper adjustments in theheating element 810 or cooling element 850. For example, the greater theflow rates, the quicker the central controller adjusts to heat or coolto keep up with the flow rates. When the flow rates are slower, smalleradjustments are made by the central controller. Similarly, for greatertemperature differences, the infusion fluid will have to be warmed, orcooled, at a higher, or lower, heat energy. The device configured inthis embodiment may be used to heat infusion fluid to temperatures inthe ranges from about 35° Celsius to about 50° Celsius, morespecifically from about 37° Celsius to about 43° Celsius. The deviceconfigured in this embodiment may be used to cool infusion fluid totemperatures in the ranges from about 0° Celsius to about 37° Celsius,more specifically from about 4° Celsius to about 25° Celsius.

Example Warming Fluid and Pumping at Variable Flow Rates

An embodiment of the infusion system under the present invention isshown in FIGS. 2a-d . The disposable cartridge 100 is shown with half ofits outer cover removed in FIG. 2a . For orientation purposes, theair-trap 110 is visible, extending out of the outer cover 201 at theright-hand portion of the figure. The outer cover of the disposable ismade of sturdy polymeric material. FIG. 2b shows the side of thedisposable cartridge which will contact the pump housing 250, shown inFIG. 2c . Again, for orientation, the air-trap 110 is shown in FIG. 2bat the left-hand portion of the figure, extending out from the outercover 201. The exposure surface 225 of the heat exchanger 101, whichwill be in contact with the heating platen 275 of the pump systemheating element 810, is shown in FIG. 2d . FIG. 2c shows the pumphousing, which contains a pumping mechanism 1020 to interact with thepump loop 104. FIG. 2c also shows the heating element 810, whichprovides the heat energy to the heat exchanger 101 contained within thedisposable cartridge 100. All elements of this Example are in fluidconnection with one another.

FIG. 2d illustrates how the disposable cartridge 100 may mate with thepump housing 250. The engaging actuator 280 allows the user to removablyattach the disposable cartridge 100 to the pump housing 250 by theclamping mechanisms 290 that extend from lock housings 285 located aboutthe platen 275. When the engaging actuator 280 is manipulated, theclamping mechanisms 290 contained within the lock housings 285 extendand engage the disposable 100 at attachment points 210 located about theexposure surface 225 of the heat exchanger 101. When engaged, thecompressive force provided to couple the exposure surface 225 of theheat exchanger 101 to the heating platen 275 is from about 100 pounds toabout 500 pounds, preferably about 200 pounds to 300 pounds, mostpreferably about 250 pounds, or alternatively about seven pounds persquare inch, distributed substantially evenly across the exposuresurface 225. Furthermore, because the pump may be used by operatorsunder exceptional stress, and in which time is of the essence, alight-weight device, allowing for simple attachment of the disposablecartridge 100, provides substantial benefit. Located between theexposure surface 225 and the platen 275 is a thermal pad 840, whichallows for extremely close and uniform contact between the platen 275and the exposure surface 225, while still conducting heat at highefficiencies between the two surfaces. The material chosen as thethermal pad 840 may be a silicone-based pad, such as CHO-THERM T500®,supplied by Chomerics, located in Woburn, Mass. The thermal pad 840allows for better heat transfer from the platen 275 to the heatexchanger 101 than an interface of air would allow. In this Example, thethermal pad 840 is about 0.01 inches thick and covers substantially theentire platen. Moreover, in this Example, the surface area of theexposure surface 225 contacting the heating the platen 275 is about 35square inches. Attaching the thermal pad 840 to only the heating platen275 is beneficial because the cartridge 100, being disposable, may beengaged and disengaged and replaced with a second cartridge 100, withoutdisrupting the integrity of the thermal pad 840.

For the purposes of this Example, the fluid being infused into thepatient is blood (although a similarly configured pump system may beused to deliver colloid, crystalloid, saline, medication, or the like).The fluid entering the pump system, embodied in this Example, may bearound 20° Celsius. The rate at which infusion is conducted is about1000 milliliters per minute. However, being driven by a motor, andcontrolled by an electronic controller, preferably a DSP controller, therapid infusion system may be capable of pumping fluid at a rate of about10 milliliters per hour to at least about 1200 milliliters per minute.Low speed operation could be used for routine IV (intra-venous)infusion; and high speed operation would be used for rapid fluidinfusion for cases such as emergency room trauma. Additionally, thedevice can be particularly advantageous in situations where it may bepreferable to first employ routine IV infusion, followed by rapidinfusion, followed again by routine infusion, such as during atransplant operation. It is also appreciated that in some embodiments,for example during emergency heart and lung support procedures, it maybe preferable to infuse blood at rates as great as about, 2000milliliters per minute to about 8000 milliliters per minute.

Conventional IV fluid, or blood bags or bottles, can be used, forexample, or an alternate fluid reservoir can be employed, particularlywhen large quantities are to be infused. The bags or bottles are spikedwith a delivery tubing that is connected to the disposable cartridge.The disposable cartridge is aligned and attached to the front of thepump housing, with pumping mechanism extending through the attacheddisposable cartridge, and communicating with the pump loop.

After the disposable cartridge 100 is attached to the pump housing 250,aligning and engaging each of the cartridge components and sensors withtheir mates, the roller pumphead of the pumping mechanism may applypumping pressure to the pump loop 104, causing fluid to flow from afluid source through the cartridge, and infusing at the desired rate.

The user may turn the pump device on by depressing the power input 1210.Next, after turning on, and before infusing fluid, the device shall beprimed. The user may use automatic priming by selecting the prime input1220, or the user may prefer to hold down the prime input 1220 so as tocause the device to be manually primed for as long as the user holdsdown the device. Priming is successful after air has been purged fromthe fluid path, and substantially all the way to the end of the patientoutflow line, by automatic or manual priming. The user may then chooseto either infuse at a standard adjustable rate by selecting the standardinfusion input 1250, infuse a bolus of either 100 milliliters, 250milliliters, 500 milliliters, or 1000 milliliters at an adjustable rateinitially set to 500 milliliters per minute, by selecting one of thebolus preset inputs 1270, or infuse at a rapid adjustable rapid rate byselecting the rapid infusion input 1260. In one embodiment, the heat ison in the default setting; thus the user does not have to selectanything to begin heating the fluid. Accordingly, the user may turn offthe heating mode by deselecting the heat input 1230. Alternatively, inanother embodiment, the heat may not be set to on in the default settingand the user thus may turn the heating mode on by selecting the heatinput 1230, and similarly turn it off by selecting it again (ordeselecting it). After the device is primed and the desired infusionmode and infusion rates are set, infusion begins when the user selectsthe start input 1285. The user may vary the infusion rate by selectingthe rate increase input 1280 or rate decrease input 1281, which causesthe electronic controller to advantageously increase or decrease thepump rate accurately to the selected, or default, infusion rate. Uponreceipt of the signal from the user interface, for example, for rapidinfusion with an increased rate of 1000 milliliters per minute, theelectronic controller 1110 sets its PWM signal duty cycle fortransmission to the motor power drive circuitry 1120, to turn the motordrive assembly at the appropriate speed. For example, to achieve a 1000milliliter per minute flow rate with a pumping mechanism 1020 thatprovides 3 milliliters of fluid per revolution and a motor that isconnected to a 14:1 gear assembly 1030, the motor needs to turn at 4667revolutions per minute.

While pumping under this scenario, LED indicators would be powered nextto the rapid infusion input, the chosen maximum pressure input, and theheat input on the user interface panel 1200. Additionally, the selectedrate indicator 1290 would display 1000, and the actual rate indicator1291 would display the rate the infusion device is actually pumping.Similarly, the status display panel 1205 may indicate that the device isoperating in rapid infusion mode, the heat is on, the sensed temperatureof the blood, the sensed pressure of the blood in the infusion tubing,as well as the total volume infused.

Again, referring to FIG. 1, the blood is drawn into the primary in-flowtube 102 and proceeds past the inflow bubble detector 120, which sends asignal to the central controller of the device if excessive bubbles orair is sensed in the infusion fluid. After passing the inflow bubbledetector, the blood passes the inflow temperature sensor 260, allowingfor proper feedback and temperature regulation. Next, the blood willpass a t-junction, which serves as the inflow pressure junction 103. Theinflow pressure junction 103 is in fluid communication with a first airchamber 151. The inflow pressure junction 103, in combination with thefirst air chamber 151 and the inflow pressure sensor 270, determines thepressure of the blood flow as it enters the pump loop 104, to allow forproper regulation of the blood flow.

The inflow pressure junction 103 monitors negative pressure, in theevent that fluid remains within the disposable cartridge but is notflowing in the direction of the patient. Such a circumstance could ariseif the fluid source bag collapses, yet fluid remains in the cartridge.If the pressure at the inflow pressure junction 103 falls below apredetermined pressure, for example, approximately 1 mmHg, then the pumpmay stop pumping.

When the blood leaves the pump loop 104, it flows through a secondt-junction, which serves as the pump outflow pressure junction 105. Thepump outflow pressure junction 105, in combination with another airchamber and the pump outflow pressure sensor 271, determines thepressure of the blood as it exits the pump loop 104, so that the flow ofthe blood through the disposable cartridge 100 can be regulated. Thepump outflow pressure junction measures the pressure of the fluidproceeding through the cartridge. Here, blockage is monitored, so thatwhen the pressure exceeds a predetermined pressure, for example,approximately 500 mmHg, the pump may shut down to avoid damage.

The blood then passes into the heat exchanger 101 via the exchangerinlet port 106. The heat exchanger 101 of this Example is created fromtwo halves, as depicted in FIG. 3. The two halves are created from thesame mold, such that inverting one mold and fixing the two togethercreates the heat exchanger. Both halves are created from the same highlyconductive material to maximize the conductive surface area againstwhich the blood will flow, thus maximizing the transfer of heat from theheat exchanger 101 to the fluid. The material used in the creation ofthe heat exchanger of this Example is anodized aluminum. The use of thismaterial accomplishes the goal of the present invention by creating alarge mass differential between the heat exchanger and the fluid, blood,to be warmed. The thermal conductivity of the anodized aluminum allowsfor excellent dissipation of heat energy across the heat exchanger. Theanodized surface of the aluminum creates a biologically inert surface toprevent either the reaction with, or adsorption of, biological material,while the blood or other fluid passes across it. In the present Example,dealing with blood, protein adsorption to the surface of the materialmay generate a trigger to the clotting cascade. The adsorbed proteins tothe inner surface of the heat exchanger, even if they do not trigger theclotting cascade, can become degraded and detach. Once detached from thesurface of the heat exchanger, these degraded, or denatured, proteinsmay react with other proteins, or the cells contained within the blood,in a deleterious manner. The anodized inner surface of the heatexchanger thus prevents damage from occurring to the blood as it passesthrough the heat exchanger.

When a disposable cartridge according to the present invention is used,the effective exchange of heat, from the heat exchanger to the fluidbeing infused, achieves the appropriate rise in temperature of thefluid, without having to expose the fluid to potentially dangeroustemperatures, as defined as a predetermined temperature limit. Insteadof having regions of varied temperature, to which the blood or fluid isexposed, the heat exchanger's constant temperature allows for moreefficient transfer of heat energy to the blood. At a flow rate of 1000milliliters per minute, achieving a fluid exit temperature of 37°Celsius means never having to expose the blood to temperatures whichcould be deleterious to the fluid being infused. In fact, using anodizedaluminum yielded a 95-96% efficiency in transferring heat energy toblood, sufficient to generate a 17° Celsius rise in temperature.

Once the blood enters the heat exchanger, the blood fills the flowcavity 304 before proceeding to traverse the entirety of the heatexchanger. The blood fills the flow cavity first, because of thenarrower flow area created by the flow fin 303 which defines the flowcavity. By creating a smaller flow path to flow over the first fin, asdepicted in FIG. 7, the blood will not traverse the long axis of theheat exchanger before it fills the flow cavity, causing the flow patternacross the heat exchanger's fins to be a wide ribbon-like shape.

The fins used in the heat exchanger, described in FIGS. 2a-d , arespaced at about 0.4 inches apart. The depth of the flow path created bythe separation of the two pluralities of fins is about 0.08 inches. Thefins are about 4.3 inches wide and 0.62 inches in height. This creates aratio of linear flow distance to width of about 1:7. The flow fin 303,as seen in FIG. 3, is wider than the remainder of fins across the heatexchanger. That increased width of the flow fin 303 creates a narrowerflow path at that fin when the two halves of the heat exchanger areconnected. In this Example, the width of the flow path created by theflow fin 303 is about 0.03 inches. Given that the blood flowing throughthe heat exchanger in this Example will preferably travel along a pathof least resistance, the flow cavity 304 will fill before the bloodtravels past the flow fin 303. The blood then travels over the finswhich creates a turbulent flow pattern for the blood as it travelsthrough the heat exchanger. This turbulent flow ensures an increasedexposure of more molecules within the blood fluid to the heat exchanger,thereby increasing the efficient transfer of heat energy.

Once the blood flow reaches the top of the heat exchanger, it exits viathe exchanger outlet port 107 located a position opposite the exchangerinlet port 106 of the heat exchanger 101. At this point, the fluid forinfusion has undergone warming and the desired temperature has beenreached. The heat exchanger temperature sensor 287 measures thetemperature of the heat exchanger 101 and provides feedback to thecentral controller for effective temperature regulation. The blood thenenters the air-trap 110 at a location approximately midway between thetop and bottom of the long-axis of the air-trap 110. In this Example,the air-trap is about 4.2 inches along its long, vertical axis and about1 inch in diameter. The air-trap intake port 503 is located about 2.1inches from the bottom of the air-trap (see FIG. 6). As the blood passesthrough the air-trap intake port, the blood travels in a clockwisedirection as the blood fills the air-trap. This clockwise flow of bloodcreates a vortex of fluid in the air-trap. The fluid flow disrupter 601,which, in this example, extends from the interior surface of the bottomof the air-trap up about 0.5 inches, creates a sufficient pressuredifferential at the fluid output port 505 to draw the blood out and notany trapped air.

Air may become trapped in the blood in this Example via severalmechanisms. Through spiking the blood, as it is attached to the pumpsystem for infusion, trapping air and in essence failing to properlypurge the source of the blood before attachment to the system. Also, theheating of the fluid itself can cause the release of stored gas withinthe blood, which may be deleterious if introduced into the patient.

As the amount of air in the air-trap 110 increases, the level of bloodin this Example, lowers within the air-trap. When the blood is below theupper level sensor interface 507 and the lower level sensor interface506, which, in this Example, are ultrasonic sensors that communicatewith the upper level sensor 246 and the lower level sensor 245,respectively, in the pump housing the level of fluid in the air-trap,the valve at the fluid output port 505 closes. When the fluid outflowflow limiting mechanism 240 is closed, compressing the primary outflowtube 108, the air output flow limiting mechanism 241 is open. Thisincreases the blood volume in the air-trap, forcing air out of the airoutput port 504. The lower level and upper level ultrasonic sensors 245,246 are located in the pump housing 250. The ultrasonic sensors utilizeenergy transmitting material, for example, silicone or urethane pads, tofacilitate the transmission of the sensor signals to the lower levelsensor interface 506 and the upper level sensor interface 507, in orderto effectively couple and measure the level of fluid within theair-trap. When the level of blood rises to or above the upper levelsensor interface 507, and thus also above the lower level sensorinterface 506, the air output flow limiting mechanism 241 closes. Atapproximately the same time that the air output flow limiting mechanism241 closes, the fluid outflow flow limiting mechanism 240 opens, andblood exits the air-trap and proceeds toward the patient.

In this Example, the fluid then passes through the fluid outflowpressure junction 135, which assists in determining the pressure forcontrolling the flow within the cartridge when based on pressure. Ifthere is blockage, and the pressure begins to rise, this device will tryto keep the pressure within an acceptable range, which can be betweenapproximately 0 mmHg and the predetermined upper limit, which in thisExample may be either 100 mmHg or 300 mmHg, depending upon what isselected by the user, by adjusting the flow rates. For example, duringoperation, the central controller will cause the dynamic range motordrive assembly to pump fluid to achieve the pre-selected rate by theuser. However, if the pressure limit is reached, the dynamic range motordrive assembly will slow, allowing the pressure to fall and then speedup again to reach the rate. If the pressure at the fluid outflowpressure junction 135 rises above a predetermined safety level, possiblydifferent than that level selectable by the user, for example, 500 mmHg,the pump may shut down.

In the present Example, however, before blood reaches the patient, itpasses through the outflow bubble detector 112. The outflow bubbledetector analyzes the blood on its way to the patient to determine thatthe air-trap removed potentially deleterious air from the system. Thebubble detector in this Example uses an ultrasonic sensor, which sends asignal across the tube. Any air bubbles present in the system willattenuate the signal. The system will shut the pump down if bubbles assmall as 30 to 50 microliters are detected. The system is able to detectbubbles of this size at the maximum flow rate of, for example, 1200milliliters per minute (in the intravenous fluid infusion example).

After passing through the outflow bubble detector 112, the fluid outflowtemperature sensor 261 uses infrared temperature detection to measurethe temperature of the blood before being delivered to the patient. Thisallows for a final temperature verification of the fluid (e.g., theblood), so as to avoid delivering overheated fluid to the patient.

Finally, after infusion, the disposable cartridge 100 may be removedfrom the pump housing 250 and may be discarded. A new disposablecartridge 100 may then be attached to the same pump housing 250 forsubsequent use. The disposability of the heat exchanger is beneficial insettings in which quick turn-around is necessary between uses, byavoiding sterilization after each use. Also, the disposable cartridge ofthe present invention, being a self-contained heating device, promotes asterile surgical field, by removing external heating mechanisms andavoiding the introduction of unnecessary foreign fluids.

Unlike standard or traditional methods of intravenous fluidadministration, the rapid infusion system described herein can providecontinuous total replacement of adult human blood volume throughvirtually any sort of hemorrhage, for an indefinite period of time, andcan rapidly regulate fluid temperature with minimal increase inresistance to flow. Additionally, the device can easily and rapidlyadminister massive quantities of blood to a single patient during asingle operation, administer physiologic fluid maintained at apredetermined temperature, at flow rates as great as 1200 millilitersper minute (or greater in other examples), and permit simultaneousdisplay and control of fluid temperature. The system can easily becarried, and is able to be quickly and easily used in emergencysituations or by emergency personnel in the field. The system can beconfigured to infuse an infinite amount of blood over an indefiniteperiod of time, based on the pump assembly employed, the tubing sizes,etc., employed.

Further, the system described in this Example may be used to infuseblood at a temperature greater than the patient's body temperature, asis advantageous in certain therapies, such as during the treatments ofviruses, for example, the hepatitis C virus. In an embodiment used towarm blood for therapeutic effects, such as systemic warming during thetreatment of the hepatitis C virus, the blood may be warmed totemperatures between about 37° Celsius and about 48° Celsius prior toinfusion to the patient. This procedure may be repeated one or moretimes, allowing the patient to cool in between each successive infusionof warmed blood. The infusion target for warming the patient may begenerally directed for systemic warming of the patient's core, or,alternatively, warming may be targeted to a specific region or organ,such as, for example, the liver.

If desired, the present invention can include multiple pumps infusingfluid to a patient through multiple catheters, thereby providing suchfluids to the patient in volumes which far exceed that possible bypresent infusion systems.

Example Cooling Fluid

In another embodiment, the pump device may be used to cool, rather thanwarm, blood or other fluid being delivered to a patient. This may beparticularly useful for patients suffering from an acute stroke, forexample, to controllably induce hypothermia by cooling the infusedblood. This embodiment operates much like the embodiment described inthe previous example, except that it includes a cooling element 850, asshown in FIG. 8b , instead of a heating element.

In this embodiment, the cooling element 850 cools the heat exchanger101, including the plurality of fins housed therein, to a temperaturelower than its ambient temperature before infusion. The infusion deviceof this embodiment may cool infusion fluid to temperatures between about0° Celsius and about 37° Celsius, more preferably between about 4°Celsius and about 25° Celsius. In this example, blood is cooled to, andmaintained at, a temperature of about 20° Celsius while flowing throughthe heat exchanger 101. After continuing through the same flow paththrough the entire disposable cartridge, the cooled blood is theninfused to the patient, for example, to the brain region. Note, however,that cooled blood, or other infusion fluids, may be infused to otherregions of a patient, which will similarly induce a controlledhypothermia. In another example, cooled blood may be intravenouslyinfused to a region near the heart for a patient suffering from an acutemyocardial infarction.

In one variation of this embodiment, the pump device may contain aheating element 810 and a cooling element 850 both, as described by thisexample. The disposable cartridge may be attached to the pump housing,so as to align with the heating element 810, or the disposable cartridgemay be attached to the pump housing, so as to align with the coolingelement 850. Thus, in this configuration, the pump device may becontrolled so as to allow the user to either deliver warm or cool bloodduring operation. This configuration would be advantageous forprocedures that benefit from interchangeably delivering volumes ofwarmed blood and cooled blood, or for warming blood to a desiredtemperature, for example, 43° Celsius, and then cooling back to bodytemperature (i.e., 37° Celsius), or vice versa. It is furtherappreciated that a second disposable cartridge, or a single disposablecartridge with a second heat exchanger, may be included with the pumpsystem, with one heat exchanger delivering warmed fluid and anotherdelivering cooled fluid.

In yet another variation, the pump device may have an interchangeableheating element and cooling element. In this configuration, the coolingelement, including the thermoelectric coolers, heating platen, andthermal pad, can replace, at will, the heating element, including thepower insulators, power resistors, heating platen, and thermal pad. Itis appreciated that only the assembly housing the power insulators andpower resistors, and the assembly housing the thermoelectric coolers maybe removable, leaving the heating platen and thermal pad remaining inthe pump housing. This interchangeable configuration is advantageousbecause it allows for rapid switching between providing cooling andwarming capabilities while still maintaining the small size thatbeneficially allows simple operation.

Example Body Temperature Regulation

In yet another embodiment, the pump device may be used to deliver largequantities of fluid in a controlled manner, and at a controlledtemperature, through the body to assist in controlling the patient'score body temperature. Certain procedures benefit from, or arepositively affected by, controllably inducing hypothermia.

In one example, saline solution is pumped through the heat exchangerincluding a cooling element 850, as in the previous example, forultimate delivery to a patient suffering from an acute myocardialinfarction. The saline solution may initially be stored at roomtemperature, for example, about 20° Celsius to about 22° Celsius, and ispreferably cooled between about 0° Celsius and about 15° Celsius. Inthis example, saline is cooled, for example, to about 10° Celsius priorto infusion. The cooled saline solution is then delivered to thepatient's bladder using a catheter. A double lumen or triple lumencatheter may be used for delivering cooled saline therethrough, and intothe bladder and replacing previously delivered fluid by evacuationthrough the catheter. In this example, the patient's bladder is cooledbecause it has a relatively large volume and is centrally located,providing a quicker, and more controlled means to cool one's coretemperature.

In another variation, the saline solution may be warmed, instead ofcooled, using a heating element in the pump housing, as in the firstexample above. Delivering warmed fluid into a centrally located volumemay be helpful, for example, when a patient is recovering from asurgical procedure under anesthesia, or when a patient is suffering fromextreme hypothermia.

Alternatively, rather than utilizing the cooling or warming capabilitiesof the pump device, pre-cooled or pre-warmed fluid may be delivered tocool or warm a patient's core temperature. In this embodiment, the pumpdevice is beneficial for controlling the flow rates and pressures,including the ability to deliver pre-warmed or pre-cooled fluids at awide range of flow rates. Controlling the flow rates will further allowmore precise control of the patient's core temperature.

It is appreciated that, in this embodiment, sensing and preventing airin the fluid path is unnecessary. The bubble detectors and air-trap maybe disabled while the device is used in this embodiment.

Example Pressure Maintenance

In yet another embodiment, the pump device may be operated as in any ofthe previous examples, however, the pump device may maintain asubstantially consistent flow pressure. The pump device in thisembodiment may maintain a relatively constant pressure, between a rangeof about 0 mmHg and about 750 mmHg, and more preferably between about 25mmHg and about 150 mmHg. This embodiment is particularly advantageousduring certain surgical procedures, such as endoscopic procedures, likearthroscopic or laparoscopic surgeries. During an arthroscopic surgery,for example, it is desirable to deliver fluid to expand the joint, aswell as to flush the surgical area and to tamponade bleeding vessels. Itmay also be desirable to warm the fluid to avoid unnecessary cooling ofthe surgical region.

Saline solution may be used as the fluid delivered in this embodiment.Each of the steps described in the first example to prepare the pumpdevice for operation, such as attaching the disposable cartridge andselecting the desired inputs, are carried out. However, under thisembodiment, the user preferably selects either the pressure increaseinput 1242, or the pressure decrease input 1244, on the user interfacepanel 1200 to pre-select the desired flow pressure maintenance level.Upon selecting one of the pressure inputs, the selected pressureindicator 1246 displays the pressure selected. In this example, the userselects the pressure increase input 1242 until 45 mmHg is displayed onthe selected pressure indicator 1246. Additionally, the user may selectthe heat input 1230 to cause the saline solution to be warmed whilecirculating through the heat exchanger 101 prior to delivery to thepatient. Finally, the primary outflow tube 111 is connected, viasurgical tubing, such as silicon tubing, to an inflow cannula, or thelike, as is typically used during arthroscopic or laparoscopicprocedures. The cannula is inserted into the patient at or near thejoint to allow accurately controlling the delivery of the fluid.

Upon beginning operation, the pump device generally operates asdescribed in the first example, warming the saline solution prior todelivery via the cannula to the patient. However, the pressure may besubstantially maintained at a selected pressure—here 45 mmHg—by thedevice central controller 1100, causing the electronic controller 1110to adjust the motor speed, thus adjusting the flow rate to substantiallymaintain a flow pressure of 45 mmHg at the pre-selected desired flowrate. A feedback loop exists from the fluid outflow pressure junction135 to the dynamic motor drive assembly, via the device centralcontroller 1100, which will allow continuous adjustments to be made tothe dynamic motor drive assembly to maintain the constant pressure. Itis further appreciated that during operation, the pressure maintenancelevels may be changed by selecting one of the pressure increase input1242 or the pressure decrease input 1244. The device used in thisembodiment may preferably deliver flow rates between about 0 millilitersper minute to about 2000 milliliters per minute.

Example Cardiopulmonary Bypass or Assist

In yet another embodiment, the pump device described herein may be usedwith patients undergoing cardiotomy, and requiring at least partialcardiopulmonary bypass or suffering from organ (heart and/or lung)failure or deterioration. The device used in this embodiment maymaintain blood circulation while preferably oxygenating the blood priorto infusion (or re-infusion). Examples of uses for which a deviceconfigured for this embodiment may be used are to provide cardiac bypassduring cardiac surgery, cardiac assist, extra-corporeal membraneoxygenation, during percutaneous heart valve replacement procedures, orduring the treatment of pneumonia, sepsis (treating and/or supportingresulting organ failure), acute respiratory distress syndrome,emphysema, chronic bronchitis, asthma with status asthmaticus, neonatalrespiratory distress syndrome, smoke inhalation, or burn victims(treating and/or supporting resulting organ failure).

A device configured for use in this embodiment may include a pumpingmechanism, a dynamic range motor drive assembly, and a centralcontroller, as described herein. Further, the device preferably includesan oxygenator in line with the infusion path. The fluid flow circuit maypreferably be configured as a closed circuit, whereby blood is drawnfrom the patient, pumped through the pump device, pumped through theoxygenator, and then re-infused to the patient. The oxygenator may beplaced distal to the dynamic range motor drive assembly prior toinfusion to the patient. The oxygenator may be a bubble oxygenator, amembrane oxygenator having multiple capillary tubes creating membranesbetween the blood and the gas, or the like, as is known in the art. Thepumping mechanism may be a roller head occlusive pump, a non-circularperistaltic pump, a centrifugal or conical pump, an impeller, or thelike, as is known in the art. The dynamic range motor drive assembly,the pumping mechanism, and the electronic controller are preferablyconfigured, so as to provide infusion flow rates up to at least 8000milliliters per minute, preferably between about 2000 milliliters perminute and about 4000 milliliters per minute. It is appreciated that apump device, configured for cardiopulmonary bypass or assist, may alsobe able to deliver fluids to a patient at slower flow rates, like thosedescribed above, such as flow rates as low as 1 milliliter per hour. Theinfusion flow pressure may also be monitored and controlled as describedabove. The pump device may also include an air-trap, so as to capturebubbles in the blood before infusion, and a thermal element, such as aheating element and/or a cooling element, as described above, so as toallow cooling or heating the blood prior to oxygenation and delivery tothe patient. A pump device used in this embodiment is particularlyadvantageous because of its manageable size and simple operation, whileallowing a wide range of infusion flow rates.

Example Dialysis

In yet another embodiment, the pump device, described herein, may beused during renal replacement therapy, such as kidney dialysis, to treatpatients with renal impairment or failure. Accordingly, this embodimentmay be used to circulate cleansed or filtered blood through a patient.

A device configured for use in this embodiment may include at least twopumping mechanisms, at least two dynamic range motor drive assemblies, acentral controller, and a dialysate bath. Accordingly, the blood may bepumped by one pumping mechanism and motor drive assembly throughmultiple capillary tubes, forming a semi-permeable membrane between thedialysate bath and the blood, as is known in the art. The dialysate maybe pumped by another pumping mechanism and motor drive assembly acrossthe capillary tubes in a direction opposite of the direction the bloodis pumped through the capillary tubes, so as to create a counter currentbath of osmotic fluid. The osmotic fluid or dialysate may include thesame, or higher, levels of physiologic electrolytes, such as salts, asnormally exist in blood, so as to force undesired solutes from the bloodto the dialysate through osmosis. Further, the dialysate may includehigher levels of bicarbonate than normally exist in the blood, so as toforce bicarbonates from the dialysate to the blood, thereby reducingacidosis, if so desired. The blood flow circuit may preferably beconfigured as a closed circuit, whereby blood is drawn from the patient,pumped through the pump device, pumped through the dialysate bath, andthen re-infused to the patient. The dialysate bath may be configured asa closed circuit or an open circuit, allowing for reuse of thedialysate, or for replenishing used dialysate with fresh dialysate, soas to maintain consistent electrolyte concentrations. A deviceconfigured for use in this embodiment may provide simple infusion flowrate control over the entire range, as disclosed herein, as well assimple dialysate bath flow rate control. The infusion flow rate maypreferably range from about 200 milliliters per minute to about 700milliliters per minute, more preferably from about 300 milliliters perminute to about 500 milliliters per minute. Though, it is appreciatedthat a pump device configured for dialysis procedures may also be ableto deliver fluids to a patient at slower flow rates, such as 1milliliter per hour, or faster flow rates, such as up to 8000milliliters per minute, as further described herein. Similarly, the flowpressure of both the dialysate and the blood infusion may also becontrolled as described herein. Like described above, the device mayalso include an air-trap and a thermal element, such as a heating and/orcooling element. A pump device configured for use during dialysisprocedures is particularly advantageous because of its portability,relative low cost, ease of use, and its robust features such as variableflow rates, heating and/or cooling, and utilizing an active air-trap.

The above description is intended to be illustrative and notrestrictive. Many embodiments will be apparent to those of skill in theart upon reading the above description. The scope of the inventionshould therefore be determined not with reference to the abovedescription, but should instead be determined with reference to theappended Claims, along with the full scope of equivalents to which suchClaims are entitled. The disclosures of all articles and referencesreferred to herein, including patents, patent applications, andpublications, are incorporated herein by reference.

What is claimed is:
 1. An infusion pump system, comprising: an infusiontubing for delivering a fluid; a heat exchanger cartridge in fluidcommunication with the infusion tubing and removably coupled to at leastone thermal element for heating or cooling the fluid; a motor drivenpump in mechanical communication with the infusion tubing and configuredto pump the fluid through the infusion tubing and the heat exchangercartridge; and a central controller in electrical communication with themotor driven pump and the at least one thermal element; wherein thecentral controller is configured to selectively deliver the fluid to apatient without heating or cooling the fluid by causing the motor drivenpump to pump the fluid through the infusion tubing and the heatexchanger cartridge while the thermal element is off.
 2. The infusionpump system of claim 1, wherein the central controller is configured todeliver the fluid without heating or cooling according to a default modeof the central controller.
 3. The infusion pump system of claim 2,further comprising a user interface in electrical communication with thecentral controller, wherein the user interface comprises a heatinginput, and wherein the central controller is configured to deliver thefluid with heating by causing the motor driven pump to pump the fluidwhile the thermal element is on in response to selection of the heatinginput.
 4. The infusion pump system of claim 2, further comprising a userinterface in electrical communication with the central controller,wherein the user interface comprises a cooling input, and wherein thecentral controller is configured to deliver the fluid with cooling bycausing the motor driven pump to pump the fluid while the thermalelement is on in response to selection of the cooling input.
 5. Theinfusion pump system of claim 1, wherein the central controller isconfigured to deliver the fluid with heating according to a default modeof the central controller.
 6. The infusion pump system of claim 5,further comprising a user interface in electrical communication with thecentral controller, wherein the user interface comprises a heatinginput, and wherein the central controller is configured to deliver thefluid without heating by causing the motor driven pump to pump the fluidwhile the thermal element is off in response to selection of the heatinginput.
 7. The infusion pump system of claim 6, wherein the userinterface further comprises a cooling input, and wherein the centralcontroller is configured to deliver the fluid with cooling by causingthe motor driven pump to pump the fluid while the thermal element is onin respond to selection of the cooling input.
 8. The infusion pumpsystem of claim 1, wherein the central controller is configured todeliver the fluid with cooling according to a default mode of thecentral controller.
 9. The infusion pump system of claim 8, furthercomprising a user interface in electrical communication with the centralcontroller, wherein the user interface comprises a cooling input, andwherein the central controller is configured to deliver the fluidwithout cooling by causing the motor driven pump to pump the fluid whilethe thermal element is off in response to selection of the coolinginput.
 10. The infusion pump system of claim 9, wherein the userinterface further comprises a heating input, and wherein the centralcontroller is configured to deliver the fluid with heating by causingthe motor driven pump to pump the fluid while the thermal element is onin respond to selection of the heating input.
 11. The infusion pumpsystem of claim 1, wherein the at least one thermal element comprises aheating element configured to heat the fluid in the heat exchangercartridge when the heating element is on.
 12. The infusion pump systemof claim 1, wherein the at least one thermal element comprises a coolingelement configured to cool the fluid in the heat exchanger cartridgewhen the cooling element is on.
 13. The infusion pump system of claim 1,wherein the at least one thermal element comprises a heating elementconfigured to heat the fluid in the heat exchanger cartridge when theheating element is on, and a cooling element configured to cool thefluid in the heat exchanger cartridge when the cooling element is on.14. The infusion pump system of claim 1, wherein the at least onethermal element comprises a heating and cooling element configured toheat the fluid in the heat exchanger cartridge when the heating andcooling element operates in a heating mode, and to cool the fluid in theheat exchanger cartridge when the heating and cooling element operatesin a cooling mode.
 15. The infusion pump system of claim 14, wherein theheating and cooling element comprises a peltier device.
 16. A method ofdelivering a fluid to a patient, the method comprising: providing aninfusion pump system comprising: an infusion tubing for delivering thefluid; a heat exchanger cartridge in fluid communication with theinfusion tubing and removably coupled to at least one thermal elementfor heating or cooling the fluid; a motor driven pump in mechanicalcommunication with the infusion tubing; and a central controller inelectrical communication with the motor driven pump and the at least onethermal element; and delivering, via the central controller, the fluidto the patient without heating or cooling the fluid by causing the motordriven pump to pump the fluid through the infusion tubing and the heatexchanger cartridge while the thermal element is off.
 17. The method ofclaim 16, wherein delivering the fluid to the patient without heating orcooling the fluid comprises delivering the fluid according to a defaultmode of the central controller.
 18. The method of claim 16, wherein theinfusion pump system further comprises a user interface in electricalcommunication with the central controller, wherein the user interfacecomprises a heating input, wherein the central controller is configuredto deliver the fluid with heating according to a default mode of thecentral controller, and wherein delivering the fluid to the patientwithout heating or cooling the fluid comprises selecting the heatinginput.
 19. The method of claim 16, wherein the infusion pump systemfurther comprises a user interface in electrical communication with thecentral controller, wherein the user interface comprises a coolinginput, wherein the central controller is configured to deliver the fluidwith cooling according to a default mode of the central controller, andwherein delivering the fluid to the patient without heating or coolingthe fluid comprises selecting the cooling input.
 20. The method of claim16, wherein the at least one thermal element comprises a heating andcooling element configured to heat the fluid in the heat exchangercartridge when the heating and cooling element operates in a heatingmode, and to cool the fluid in the heat exchanger cartridge when theheating and cooling element operates in a cooling mode.